The Dark Horse Universe was a continuity that existed between 1994 and 1996 in a Dark Horse imprint called Comic's Greatest World and later renamed Dark Horse Heroes. Recently, the continuity was rebooted with new heroes and new incarnations of older heroes.
It should be noted that not all super-hero comics published by Dark Horse take place in the same continuity. For example, Hellboy is not part of this Dark Horse universe and, due to the fact that he is creator owned, often appear and other company's comics. Vortex