Most aliens speak English.

It may be British English, American English, or Australian English, but indeed, most aliens speak English. Perhaps this all began because "a long time ago in a galaxy far, far away" many spoke English. Maybe that's where we learned the language from. At the time of the Stargate film in 1994, aliens in the Stargate universe did not in fact speak English. Between 1994 and the beginning of 1997 series, aliens in multiple galaxies had all learned English. Perhaps Daniel Jackson taught them while he was living on another planet or they simply heard Earthlings were coming (just the American English speaking kind) and they wanted to be prepared. I appreciate the effort, especially in such a short time.

Interestingly, the aliens I see via Doctor Who all speak British English, including the Doctor himself and the evil Daleks. In Battlestar Gallactica, they are humans, but human aliens with no contact with earth. True, they speak a frakked-up form of American, but the persistence of this language across galaxies is uncanny.

There are a few aliens out there who don't speak English, such as all sorts of species in Star Trek and in Farscape. Apparently those crews were able to travel far enough to find areas of space that English hadn't pervaded, at least until a wormhole brought Ben Browder and Claudia Black to Stargate Command and the world of English-speaking aliens. Oddly though, the translator microbes in Farscape gave an Australian accent to those speaking, even though the listener spoke with an American accent. What an odd translation quirk!

The tenacious Star Trek crew was able to understand alien-speak via the "universal translator." The universal translator worked on the basic scientific principle of magic. With a click of a button, magically everyone could understand each other and the camera could record English-speak. For the uninitiated, "universal translator" is code for "writers' pitiful attempt to deal with alien communication problems." At least they made an attempt, albeit a sad one.

The influence of English across the universe is amazing and unbounded. With this sort of power, I don't see how non-English speaking cultures here on Earth have any hope.