Earth-616

Earth-616 is the "official" designation of the particular parallel Earth on which the majority of Marvel Comcs characters live, including (obviously) most of those created by Marvel UK; it is, essentially, the mainstream Marvel Universe. All of Marvel's various alternate Earths have numerical designations, other notable ones including Earth-238 (the "Crooked World" from the Captain Britain stories by Dave Thorpe and Alan Moore), Earth 33 1/3 (the cartoon world of characters such as The Fairly Amazing Spider-Hound, Earth-5556 (the Earth inhabited by characters from Marvel UK's licensed Doctor Who comics, such as Sharon Davies and Gus Goodman) and Earth-712 (the reality of the Squadron Supreme). Prominent characters existing on Earth-616 include Spider-Man (Peter Parker), Captain Britain (Brian Braddock), Captain America, Thor, Hulk (Bruce Banner), Black Knight, Motormouth, Union Jack, Nick Fury, the Knights of Pendragon and the X-Men.

It is satisfying to note that the designation "Earth-616", which is now used throughout the Marvel Universe and its associated fandom, was actually coined in a Marvel UK title; Dave Thorpe apparently used it in his Captain Britain series in Marvel Super-Heroes Monthly Vol 1 as a kind of joke, since 616 is apparently one of the numbers associated with the Devil of Christian mythology, and Thorpe disliked superheroes.