You've seen the original film, and maybe the Holiday Special... but how about The Richard Pryor Show? In 1977 the comic was given the masks, with which he mixed-and-matched costumes, to make a comedy sketch that shows some extended shots of many famous rubber faces. It also shows how cheap the masks were when not edited properly, but you'll see familiar faces like Pons Limbic (Brainiac), Momaw Nadon (Hammerhead), and Muftak - with pants and suspenders, no less. I don't know how "canon" any of this is, but remixed aliens are a fascinating thing and you can see them below.

Tell your friends, this could be a great resource for new alien figures to ask for that we'll never, ever get.