Super Mario Galaxy

[Ichimonji]

You can only get a max of 105 stars before you beat the game. The last 15 will be unlocked to obtain after completion. So, before the game is complete you should do the three normal missions, one comet, and one hidden for all the major galaxies. There are also three green stars, and all the hungry luma stars. Oh, and don't forget the red star at the Gate. After you beat it, all the Purple comet stars will be unlocked for the levels.

I have 114 stars so far.
As of right now, I have 120 stars! Awesome.