If you are building your own artwork, or animations, or videos, or perhaps a button set for a web site, it can be fun and useful to have some Science Fiction Fonts in your toolkit to give a bit of flavor to your creations. A great place to start is with the complete Futurama suite. It has both of the alien languages fonts (and if you didn’t already translate all the jokes on the signs that use them, you may want to go back and re-watch some of the episodes, with you cheat sheet close to hand) as well as the Title, Ambient, and Bold Fonts used in the series. The RoboCop font is a classic, Back To The Future is a good choice, Alien is a classic, and Splash Gordon is also quite a good catch. Because of the way that last web site does everything server side with Javascript, that link only gets you to the site. You will have to drill down to get to the font itself.
There are a number of other series that make their font set available which you should search out, but you will also find some quality resources at the font compilation sites. 1001 Fonts includes 137 free Sci-Fi/Fantasy Fonts, and Da Font has several hundred more, for instance. FontSpace includes a bunch more, as does Fonts2U. Note that on several of these sites you will get different results with different search terms; try several of them and see what other goodies you come across.