Note: This answer is full of spoilers - so many that it would be impossible to spoiler-tag all of them - so if you haven't finished the series and want to avoid spoilers, don't read it.
TL;DR: We don't know for sure, but the people who did make the list have some things in common. Each person on Roland's list falls into one or more of these categories:
Having been a member of one of Roland's Ka Tets
Having been loved and/or respected by Roland
Having died for the cause of the White, or for the Tower itself
Having done something that was necessary for Roland to reach the Tower
Having died, and Roland having blamed himself for it
Having simply asked to be included in the list (this only applies to Aunt Talitha)
And with just a single exception (i.e., Stephen King himself), everyone has one thing in common:
- The bulk of their interaction with Roland took place in Roland's world (All-World), not our world (Keystone World).
Who made the cut:
Here's a graph of who made the list, and which of the above criteria each of them met:
Alain Johns - Member of Roland's first Ka Tet; loved deeply by Roland from childhood; died for the Tower
Aunt Talitha - Her gift to Roland - a necklace - ended up making it possible to save the Tower, although she didn't know this would happen; Roland had also promised to call her name when he reached the Tower because she asked him to, and she had been generous to Roland's final Ka Tet.
Cortland Andrus - Roland loved and respected him; he was a champion of the White and was killed for it.
Cuthbert Allgood - Member of Roland's first Ka Tet; loved deeply by Roland from childhood - he was actually Roland's best friend; died for the Tower
David the hawk - Roland sent David to his death in order to pass his trial by combat and become a gunslinger.
Dinky Earnshaw - Made it possible for the Tower to survive.
Eddie Dean - Member of Roland's final Ka Tet; died for the Tower; deeply beloved to, and respected by, Roland.
Gabrielle Deschain - Roland's beloved mother, who died by Roland's hand.
Hax the Cook - Beloved by Roland (before his treason); died because Roland reported his crimes
Jake Chambers - Member of Roland's final Ka Tet; beloved by Roland; died for the Tower; Roland blames himself for his death.
Jamie DeCurry - Member of Roland's first Ka Tet; loved deeply by Roland from childhood; died for the Tower
Oy the Brave - Member of Roland's final Ka Tet; beloved by Roland; died for the Tower - and literally died to save Roland's life; Roland blames himself for his death.
Pere Callahan - Died for the Tower; Roland blames himself for his death
Sheemie Ruiz - Member of Roland's first Ka Tet; beloved to Roland; died for the Tower; Roland blames himself for his death.
Stephen King - Made it possible for Roland to reach the Tower (and indeed, he may have created Roland and the Tower, and sent Roland on the quest) - although Roland didn't like (let alone love) him, and certainly didn't respect him.
Steven Deschain - Roland's beloved and respected father who died for the White.
Susan Delgado - Member of Roland's first Ka Tet; Roland's first (and only) true romantic love; Roland blames himself for her death.
Susannah Dean - Member of Roland's final Ka Tet; deeply beloved and respected by Roland
Ted Brautigan - Made it possible for Roland to reach the Tower
Vannay the Wise - Beloved and respected by Roland from childhood; died in the service of the White.
Who didn't make the cut:
Roland and Eddie knew Calvin was an integral part of saving the Tower, but he played his part totally unwillingly. He had to be cajoled, threatened, and harangued endlessly before he agreed to do the right thing, and even after he did agree, he repeatedly tried to renege. Roland and Eddie see him as greedy, selfish, stupid, weak, obstinate, and generally unlikable. More than once, Roland and Eddie express a desire to kill him. They don't love him, they don't like him, and they don't respect him.
Their feelings towards Calvin are somewhat similar to their feelings towards Stephen King, but there is a crucial difference between King and Calvin:
King needs to be prodded along from time to time before he does his part, but he fulfills his role willingly, and on several occasions, he goes out of his way to help Roland achieve his goals, even though he knows that doing so puts his own life in jeopardy. King's reluctance to write the story is his only real failing, but he has every reason to be reluctant - every time he thinks about the Tower, the Crimson King tries to kill him. This makes it all the more impressive that King always manages to bite the bullet and do his part, and it takes relatively little effort on Roland's part to convince him to do so.
Calvin, on the other hand, has to be dragged kicking and screaming into doing far less significant things for Roland and the White, and even then, he never does anything without getting something in return. What's worse, when he demands compensation for his meager contributions, hems and haws, tries to back out of his obligations, and makes everything far more difficult than it should be, he does so out of greedy self-interest, not out of fear of death. Once Calvin allows the Tet Corporation to take ownership of his property (the vacant lot housing the Rose, at Second Ave. and 47th St.), the people who are trying to destroy the Tower have no interest in Calvin, because he has nothing they want, and hurting him won't help them achieve their goal. Unlike King, Calvin's refusal to cooperate is motivated purely by greed - he has nothing on the line, and he isn't asked for much, but he makes everyone around him go through hell to contribute the minuscule amount that is asked of him.
I admit that Roland's failure to mention Deepneau at the Tower is much harder to explain. Deepneau had very little reason to help Roland and Eddie - he had no real connection to the Tower, and could have simply walked away from the whole mess as soon as he met the gunslingers. He only became involved because he was Calvin's friend, he knew that the quest was of the greatest possible importance, and he knew that Calvin wouldn't do his part willingly. Deepneau was an old man with no apparent part to play in the quest, and he was dying of cancer when Roland and Eddie came into his life.
Still, he pledged himself to the cause of the White. He knew that doing so would make him the enemy of powerful forces - the forces of the Red, the Crimson King, and all those who wanted to destroy the Tower. He knew that his decision would jeopardize himself and those he loved, and would bring him endless hassles, headaches, and frustration (mostly from his nonstop efforts to convince the obstinate Calvin Tower to do the right thing). He had no reason to help Roland, and Roland had no right to expect Deepneau's assistance; still, Deepneau spent the rest of his life tirelessly working to ensure the survival of the Tower and the success of Roland's quest.
Aaron Deepneau finally died of cancer in 1992, some 15 years after meeting Roland and Eddie, having spent those years on Tet Corporation's Board of Directors, pursuing Roland's goals in Keystone World. His last words show the depth of his commitment to the Tower:
Tell Roland we did our best.
- The Dark Tower, Book VII: The Dark Tower, by Stephen King
Like Deepneau, it is hard to explain why Roland didn't call John's name at the Tower. Like Deepneau, Cullum had no reason to get involved in Roland's quest. Like Deepneau, Cullum had no obvious part to play in the fate of the Tower. Like Deepneau, Cullum stood to lose much and gain little by pledging his life to the cause of the White and the Tower. Like Deepneau, Cullum made this pledge anyway.
Roland and Eddie meet Cullum in the most random, unanticipated manner imaginable: he just happened to be at the General Store in Stoneham when the gunslingers appear and are attacked by Andolini and the rest of Balazar's thugs. Any sane person would have run away and never looked back, but Cullum instantly fell in behind the gunslingers and joined the battle, without even knowing who the combatants were or why they were fighting. Roland and Eddie had no reason to even think of asking him for assistance, and they didn't ask for it; he just jumped in and started helping.
Deepneau's only connection to the Tower was by virtue of his friendship with Calvin; Cullum's connection to the Tower was even more tenuous - he just happened to be in the same place as Roland and Eddie one day. The gunslingers had no right to expect anything from him, but he gave them everything, and risked everything to help them. He has no reason to lift a finger for these strange men wielding ancient revolvers, but he devotes his life to their quest. In fact, we learn in the last volume of the series, The Dark Tower, Book VII: The Dark Tower, that Cullum actually gave his life for the cause. After spending more than a decade on the Tet Corporation's Board of Directors, conducting guerrilla warfare against Sombra Corporation and North Central Positronics, he was shot and killed by a Can-Toi assassin in 1989.
The aforementioned elderly millionaire. Moses was Susannah's godfather, and he was already 78 years old when two strangers - John Cullum and Aaron Deepneau - came to him claiming to bear a message from his goddaughter, who had disappeared some 14 years earlier. He heard their story about an imperiled magical Tower, upon which the fate of all existence depended. He watched as Cullum blew onto the necklace Roland had received from Aunt Talitha and passed on to Cullum, and heard a Susannah's voice speaking from the ancient crucifix. That was all it took for Carver to forfeit his fortune and devote the rest of his life to Roland, the Tower, and the White.
When Roland first meets him in 1999, Moses is 100 years old, and the last surviving member of Tet Corporation's "founding fathers". Two years earlier, he surrendered command of the company to his daughter Marion, but is still actively engaged in the war against the Crimson King and the Red. Roland recognizes Moses and Marion as born gunslingers right away, and Roland and Moses share a deep mutual respect - perhaps even reverence - immediately:
[Moses] put his loosely clenched, arthritic fist to his forehead, then bent his right knee, taking all of his weight on his trembling right leg. “Hile you last gunslinger, Roland Deschain out of Gilead, son of Steven and true descendent of Arthur Eld. I, the last of what was called among ourselves the Ka-Tet of the Rose, salute you.”
Roland put his own fisted hand to his forehead and did more than make a leg; he went to his knee. “Hile Daddy Mose, godfather of Susannah, dinh of the Ka-Tet of the Rose, I salute you with my heart.”
- The Dark Tower, Book VII: The Dark Tower, by Stephen King
Again, it is hard to explain Roland's failure to call Moses' name at the Tower, except perhaps from an out-of-universe perspective: he entered the story very late, and although he played an important role in protecting the Tower in-universe, he appears in person only once in the books, and the entirety of his appearance takes up only a few pages.
Patrick is a minor character, out-of-universe, but plays a pivotal role in Roland's success, in-universe. He is the only person who accompanied Roland to the Tower, yet Roland doesn't include him in the list of names. I, like many fans of the series, was a bit peeved that such a Johnny-come-lately, who did some important things, but whose irresponsibility got Oy killed, was Roland's sole companion at the Tower. So many people - particularly Roland's entire Ka Tet - did so much to reach the Tower, but didn't make it. Patrick did relatively little, but reaped the ultimate reward.
King may well have foreseen the fans' dissatisfaction with this, and decided to avoid even more outrage by having Roland omit Patrick from his speech at the Tower. Or King may have thought that Roland realized that Patrick's presence at the Tower was a reflection of necessity rather than merit. In any case, I would argue that Patrick, like Calvin, simply didn't deserve to be treated as the equal of the far more important and admirable characters whose names Roland proclaimed at the Tower.
Speculation on why Roland excluded people like Deepneau, Cullum, Carver, and Danville:
Aside from the criteria I've mentioned above, virtually all of the people whose names Roland called out at the foot of the Tower have one thing in common:
Roland's relationships with each of them took place primarily in his world (All-World), not our world (Keystone World).
There is only one exception to this rule - Stephen King. But although King never actually appears in All-World, he basically created All-World. This might be the reason that he alone, of all the people who aided Roland in Keystone World, was deemed worthy of having his name proclaimed at the hub of all universes.
And of the people whose names Roland didn't speak at the Tower, all were originally from Keystone World, and all but Patrick were people Roland knew exclusively in Keystone World.
King might have thought that some characters - like Deepneau, Cullum, and Carver from Keystone World, and Patrick Danville from All-World - were too minor, out-of-universe, to be deemed worthy by the fans, and he may have thought them unworthy himself.
Update: Word of God:
I contacted Robin Furth - King's research assistant, writer of the Dark Tower comics, and author of The Dark Tower: The Complete Concordance. I consider her opinion "word of god" because she writes for the franchise, and because her Complete Concordance was actually written for King's personal use as a reference tool. Because he wrote the Dark Tower series in eight volumes over 35 years, he had trouble keeping track of all the elements he had introduced in earlier volumes while he was writing the later installments, and she composed the Concordance to help him keep his facts straight. Later, he convinced her to publish the Concordance so fans would have access to it as well.
Anyway, Sai Furth read my answer and replied:
Hey Wad! Loved your article. It is a brilliant piece of work. I agree with everything you say. You’re right--all the names that Roland calls out (except for Stephen King’s) are people who have spent time in Mid-World or End-World (David the hawk is an honorary person in this case!). All of them have made great sacrifices to keep Mid-World, End-World, and the Tower, safe. They are all, in one way or another, associated with Tower Keystone, which is Roland’s world. Stephen King is a world-maker, and so is inevitably associated with Tower Keystone. They are all people to whom Roland owes a debt. Either they gave their lives to his cause, or somehow or other, Roland brought about their deaths (and then, as you say, there is Aunt Talitha, an old woman who remembered the White through evil days, and who gave Roland a cross to lay at the foot of the Tower...).
Interestingly, three of the “our world” people that Roland names are actually from alternate earths, not Keystone Earth. We know that Eddie, Susannah, and Ted come from alternate earths. In Eddie’s world, Co-Op City is in Brooklyn, in Susannah’s, the A trains stops at Christopher Street Station, and Ted tells us outright that he’s not from Keystone. Since Dinky exists in the short story, “Everything’s Eventual,” there’s a good chance that he, too, belongs to one of the alternate earths created by Stephen King. The same goes for Jake (After all, Jake dies and yet comes back to life. But on Keystone Earth, what’s done can’t be undone. In other words, alas, dead is dead...).
All of the people who Roland does NOT name (except for Patrick) are associated with Tet Corporation. Tet is firmly based on Keystone Earth--a place where the Tower takes the form of a rose. None (except for Patrick) have ever visited Mid-World or End-World (even Calvin Tower is tied to Tet. The Calvins are named for him, and he came up with the idea of employing psychics, or Tet’s “Good Mind” Folk...).
Perhaps, for those of us who belong to Keystone Earth, salvation will come another way?
One thought about Patrick. The Tower is a place haunted by Roland’s ghosts. Since Roland sends Patrick back to the Federal just moments before he calls out his list, he knows for certain that Patrick is alive. Those whose names Roland calls are either dead or missing...
Once again, fantastic job!
Long days and pleasant nights, sai!
Robin of the Calvins
PS: Please feel free to post this if you think people might be interested.
- Robin Furth, personal correspondence
Note: I also got in touch with Bev Vincent (author of The Dark Tower Companion and The Road to the Dark Tower: Exploring Stephen King's Magnum Opus) about this question, and he said:
Off the top of my head, I think he named people from his ka-tets. I don't think Deepnau [sic] qualifies.
- Bev Vincent, personal correspondence
When I pointed out that many of the people Roland named (i.e., Talitha, Cort, David, Dinky, Gabrielle, Hax, Callahan, King, Steven, Ted, Vannay) were never members of his Ka Tets, he replied:
I don't have a definitive answer for you, I'm afraid.
- Bev Vincent, personal correspondence