Well, here are the answers. The following are genuine figures from the art world, whose existence can be verified at the Getty Institute database:
- Ecke Bonk, a German artist (born 1953)
- Hieronymous Cock, a Dutch artist (1510-1570)
- Linnaeus Tripe, an English photographer (1822-1902)
- James Arliss Bumgardner, an American painter (born 1935)
- Illarion Ivanov-Shits, a Russian architect (1865-1937)
This of course means that Balthazar Ommegod, Wilfred Cranny-Ashe, Narcissus Licker, Wout Slutti, and Tikki Bochs (sorry, couldn't resist!) are all complete fabrications.
However, I drew the line at including the genuine mid-18th-century Chinese painter Yi Fu-chiu, who was also known by the name Fukyu...