I guess I would also have to nominate Zecharia Sitchin, of course. There's a lot of bad astronomy asociated with Planet X, in all its convoluted forms and derivations. Maybe too many Planet X inductees?

So, we have for our consideration:

Nancy Leider (Planet X)
James McCanney (Comet/Planet Theories)
Bart Sibrel (Lunary Landing Conspiracy)
Velikovsky (Worlds in Collision)
Zecharia Sitchin (Nibiru)

A lot of these folks would make a "Bad History Hall of Fame" list as well as a great softball team.

Avian