Birk and I have a game we play during the credits of every movie we watch: find an Alex.
We haven't failed yet.
In a pinch, a last name like Alexander will count, but so far, we have always found a first name of Alex, Alexander, Alexandra, Alexandria, Alexandrea, Alexis, Alek, Alec, Aleksander... you get the idea.
So far, we haven't had to make a call on whether names like Lex or Lexi or Xander count, but I think if we can count a last name, we can count a nickname or short-form like that.
One thing I've noticed: rarely do you find our kind (the Alex kind) in the list of actors. The only one I can think of in recent memory is Alec Baldwin (and that was TV; we were watching "30 Rock"). Maybe if we watched something with Alexis Bledel in it...? But usually we find them in the sections like CGI or costuming or Production Coordinators (there were two Alexes in that section for Harry Potter and the Deathly Hallows, Pt. 1... which I am currently watching the credits for, and which prompted this post).
At any rate, we have a fun time with it.