Purple People Eater is based loosely (very loosely) on the song of the same name made popular by Sheb Wooley. In this movie version, Neil Patrick Harris finds some old records which once belonged to his father. When Neil plays Wooley's song, the purple people eater comes down from space. No reason given, it just happens. Purple people eater is one horned and one eyed, but only eats purple people. He's like a big goofy stuffed animal (or a ballpark mascot) and Neil names him Purple. Purple can play the horn out of the top of his head (and sometimes, actual notes are present on screen), so him and Neil form a band, which becomes famous locally and they even cut a record. They use their fame to do a benefit to save some old folks from getting kicked out of their homes by a greedy developer.
There are three musicians of note in Purple People Eater: Chubby Checker makes a guest appearance with the band and sings "Twist It Up ". Sheb Wooley has a part as an old friend of Neil's grandfather and Little Richard appears at the end of the film as the mayor of the town and helps get an ordinance passed saving the old folks from having their rental homes turned into expensive condos.
I'm not going to be too harsh on Purple People Eater because it's really a movie for kids....and I'm a long way from being a kid. For an adult, it's pretty dull with a weak plot and even the acting isn't very good; but I bet there are kids out there who have watched, or would watch this film over and over again.