One. And I enjoyed the games enough that I did a couple of playthroughs with that one, as the same class, making all the same decisions. When a game is as heavily written and story oriented as Mass Effect, I just CANNOT play through as a different gender, or with different looks, or doing/saying different things. In my head, Shepard looks and talks and acts a certain way. I don't want to watch a LOTR where Frodo is suddenly a heavyset, fast talking Asian brawler, and I don't want to play a Mass Effect where Shepard is completely different. My head will just be screaming "That's not Shepard" the entire time.
Yes, I know. I'm crazy.
Yes, I know. I'm crazy.