I was rewatching the Harry Potter series and in the seventh film, Harry visits the grave of his parents. I couldn't help questioning whether this is a cultural tradition (i.e. because they are British who are mainly Christians and normally practice burials) or whether all wizards and witches regardless of origin are buried. It is trivial (probably) to say that muggles face different methods of departure. Has there ever been wizards/witches who are cremated or faced a different fate after death?
The Tales of Beedle the Bard suggests that some wands are burned with their owners, implying that the owners themselves are cremated.
The general practice of burying (or burning) the wand with its owner, once he or she has died, also tends to prevent any individual wand learning from too many masters.
—The Tales of Beedle the Bard
There have't been any intentional cremations described in the books. There has been at least one unintentional cremation, that of Vincent Crabbe, who conjured Fiendfyre and was consumed by it:
“C-Crabbe,” choked Malfoy as soon as he could speak. “C-Crabbe . . . ”
“He’s dead,” said Ron harshly.
—Harry Potter and the Deathly Hallows
The clear implication from Dumbledore's annotated copy of The Tales of Beedle the Bard is that lots of witches and wizards have been cremated. In fact, their muggle friends were kind enough to even save them the effort of dying first.
Beedle was somewhat out of step with his times in preaching a message of brotherly love for Muggles. The persecution of witches and wizards was gathering pace all over Europe in the early fifteenth century. Many in the magical community felt, and with good reason, that offering to cast a spell on the Muggle next door’s sickly pig was tantamount to volunteering to fetch the firewood for one’s own funeral pyre.
Within the novels and Pottermore, of the six funerals that we see (Dumbledore, Aragog, Ariana Dumbledore, Dobby, Elphinstone Urquart) all involve a burial or an internment. The closest we get to a cremation is Dumbledore's fancy entombment in Half Blood Prince.
The little man in black had stopped speaking at last and resumed his seat. Harry waited for somebody else to get to their feet; he expected speeches, probably from the Minister, but nobody moved. Then several people screamed.
Bright, white flames had erupted around Dumbledore’s body and the table upon which it lay: higher and higher they rose, obscuring the body. White smoke spiralled into the air and made strange shapes: Harry thought, for one heart-stopping moment, that he saw a phoenix fly joyfully into the blue, but next second the fire had vanished. In its place was a white marble tomb, encasing Dumbledore’s body and the table on which he had rested.
According to the movie (HP5, Order of the Phoenix), Sirius doesn't even leave a body; he just passes through the Veil. So in at least one instance, there is nothing to bury, cremate, or otherwise handle.
In the movie, at the Battle of Hogwarts (HP7, Deathly Hallows), at least three Snatchers are shown disintegrating on contact with the school grounds's protective enchantments (leading the rest of the Snatchers to hang back until the enchantments collapse). Again, no remains remained. This suggests that disintegration of wizards was not rare during the Wizarding Wars.
The absence of remains does not prevent placement of a headstone. So depending on the exact intent of your question, we could either observe that in some instances there are no remains, so the answer to your question is "yes", but exhaustively determining that every case of a death without remains resulted in placement of a monument would be infeasible in-universe and is impossible out-of-universe.