Any list of reptilian aliens would be incomplete without Grig from The Last Starfighter.
This fella is an example of a benevolent fatherly alien, its iguana-like appearance notwithstanding. Not that I have anything against iguanas. All I'm saying is that it is wise, loyal, caring, and has a trademark cackle.
This reptilian humanoid alien is a star navigator first class in a Rylan Star League army. He lives on a rocky planet in underground caves. He has a "wife-oid" and 6000 kids. He is senselessly brave and, as he himself admits, he has always wanted to fight a desperate battle against incredible odds.
Watching this movie as a kid helped me get over my fear of reptiles, which worked well for me in biology class. (Who says science fiction movies serve no practical purpose?!)