That depends on the breed. My pit bull's name is Hemi...I probably also could have gone with Taz or some other label that denotes mayhem and rebellion since he has decided that he is the pack leader in my house and I am no longer the Alpha.
If it's a bulldog, you have to go with "Winston." I'm also a fan of Brewster, Champ, Wiggles, and Duke. Diogie (pronounced D-O-G) is also clever.