A black-and-white checkered Dalmation.
what would be a good chess.com mascot????

Read this and you'll see that it's quite obvious it would be a pawn: http://www.chess.com/blog/view/why-the-pawn-in-the-chesscom-

If I am playing chess against someone in OTB, I get to see what they look like.
Is chess on the internet a masquerade? Why don't players simply post their own photo?
Of course, I could postulate at least a half dozen reasons...celebrity incognito, too ugly, too handsome/beautiful, too young, too old, wanted by the police, worried about being kidnapped, bald, flat chested, too fat, too skinny, purple hair and a nose ring, non-purple hair and no nose ring...
All I can say, in a word, is: Bah humbug!!!
(Sorry, that was two words...Bah! would suffice.)
owl with eyeglasses perched on a chessboard???