ALF, on NBC
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So there was this alien named Gordon Shumway, who crashed his spaceship into the garage roof of the Tanner family, after his home planet of Melmac blew up. Willie Tanner called him an "Alf," an acronym for "Alien Life Form," so his real name was rarely used by anyone, throughout the series. Anyway, the Tanners kept him hidden from the authorities, fearing that if they discovered an alien living on Earth, they'd, like, lock him up and do all kinds of experiments on him, maybe kill him, whatever. In spite of the serious nature of being one of very few survivors from Melmac (and having no contact with any of the others), and worrying about what the government would do if they found him, the show was mostly built on rather goofy humor. ALF himself became friends with the Tanners' young son, Brian, but for the most part he annoyed Willie and especially his wife, Kate. Their teenage daughter, Lynn, was mostly indifferent to him. The Tanners also had a couple of neighbors, Trevor and Raquel Ochmonek, though I don't remember them well. (They didn't know about ALF.) Anyway, ALF could be kind of obnoxious, in a light-hearted way. And he often tried to eat the Tanners' cat, Lucky (because cats were considered food by Melmackians). And I don't really know what else to say, except that the whole show was kind of ridiculous, but funny, with rare moments of personal drama.
Also, the series ended on a cliffhanger, in which ALF was captured by the government. In 1996, six years after NBC cancelled the series, the cliffhanger was finally resolved when ABC aired a TV movie called "Project ALF" (in which the Tanners don't appear). I don't remember if I saw it then, or sometime later, nor do I actually remember the plot very well. Someday I should probably try to watch it again, so I can write a review. And there was an animated series (see other cartoons), a prequel set on Melmac. (There was also a different animated series that I never saw.) And of course ALF did commercials, there was tons of merchandise (I remember having a set of Bouillabaisseball cards), and in 2004, ALF hosted a talk show on TV Land (which lasted 7 episodes, but I think I saw maybe one of them).
Oh, and one other completely random thing I wanted to mention. ALF always used to make puns based on Kate's name, and I seem to recall learning about Kathmandu in Social Studies or something, and thinking ALF should call her "Katemandu," and then probably like the next episode I saw, he did exactly that. Maybe it wasn't the very next episode, I don't remember. I was a kid and it was a long time ago. But I do remember thinking it was a neat coincidence.