I have several dozen: William Shatner, Leonard Nimoy, DeForest Kelley, Nichelle Nichols, Walter Koenig, George Takei, Patrick Stewart, Jonathan Frakes, Levar Burton, Denise Crosby, Michael Dorn, Gates McFadden, Marina Sirtis, Brent Spiner, Rene Auberjonois, Cirroc Lofton, Aron Eisenberg, J.G. Hertzler, Max Grodenchik, Chase Masterson, Nicole deBoer, Casey Biggs, Robert O'Reilly, Robert Beltran, Roxann Dawson, Ethan Phillips, Robert Picardo, Tim Russ, Garrett Wang, Vaughn Armstrong, John de Lancie, Dominic Keating, John Billingsley, Anthony Montgomery, Linda Park, Connor Trinneer, Bruce Hyde, Peter Mayhew, David Prowse, Bruce Davison, Mira Furlan, Amber Benson, Mary McDonnell, Malcolm McDowell, Michael Hogan, Adam West, Christopher Judge, Ellen Muth, Matthew Waterhouse, J. August Richards, Andy Hallett, Ben Browder, Claudia Black, Robert Englund, Mickey Rooney, Chris Owens, Nicholas Brendon, Harry Groener, Ron Glass, Neil Raiment, Adrian Raiment, Gareth David Lloyd, Kevin Sorbo, George Hertzberg, Michelle Forbes, James Marsters, James C. Leary, Elijah Wood, Matt Frewer, Rainbow Sun Francks, Colin Ferguson, Stewart Moss, Adam Busch, Dean Stockwell, Julie Benz, Ray Park, Teryl Rothery, Lou Ferrigno, Mark Lenard, Mandy Patinkin, D.C. Fontana, Robert J. Sawyer, Garfield & Judith Reeves-Stevens, Harry Turtledove, David Feintuch, David Nickle, Terry Pratchett, Orson Scott Card (forgive me, it was before I knew about his political/social beliefs), Keith R. A. DeCandido, Tanya Huff, and Monty Hall.
I may have left a few names off that list (particularly authors: I've met so many, but I don't often have a book with me for them to sign - I'm kicking myself that I didn't have my Dresden Files books with me when I met Jim Butcher).
I know that when I was a kid, I had several sports stars' autographs as well, but my autograph book went missing when I was about 13. And I had Paul Henderson in there, too.
