The only ones whose names are confirmed (or practically confirmed) are William Shakespeare (presumably), Carl Conrad Coreander and Bastian Balthazar Bux.
However, we do have the descriptions of several other unnamed Humans ('Know-Nothings') who ended up in the City of the Old Emperors:
- A man who pushes a cart
- A woman who then pushes that cart
- A woman trying to spear peas
- A little girl struggling to push a doll's carriage with square wheels
- A man shaving a mirror
- A boy with a heavy hammer trying to drive nails into a pair of socks
- A fat man trying to paste postage stamps on soap bubbles
So a total of 10 individually identified or described Humans have visited Fantastica. But only 3 named.
On a side note I've always found the boy and girl's presence disturbing. This means at least two children came to Fantastica, gave the Childlike Empress a name, tried to overthrow her, and essentially had death of personality, trapped in a place where they will never die or even age, forever.
How long have they been there? Hundreds of years? Or could they be missing persons cases from Bastian's era, who went to an attic or library corner, started reading, and never returned?
I know you asked for names, so I might be skirting around the question here.