BSD Daemon
From instapedia.com
The BSD daemon was first drawn in 1976 by comic artist Phil Foglio. Developer Mike O'Brien, who was working as a bonded locksmith at the time, opened a wall safe in Foglio's Chicago apartment after a roommate had "split town" without leaving the combination. In return Foglio agreed to draw T-shirt artwork for O'Brien, who gave him some Polaroid snaps of a PDP-11 system running UNIX along with some notions about visual puns having to do with pipes, demons/daemons, forks, a "bit bucket" named /dev/null and so on.[3] Foglio's drawing showed four happy little red daemon characters carrying tridents and climbing about on (or falling off of) water pipes in front of a caricature of a PDP-11 and was used for the first national UNIX meeting in the US (which was held in Urbana, Illinois). Bell Labs bought dozens of T-shirts featuring this drawing, which subsequently appeared on UNIX T-shirts for about a decade. Usenix purchased the reproduction rights to Foglio's artwork in 1986. His original drawing was then apparently mislaid and lost shortly after having been sent to Digital Equipment Corporation for use in an advertisement and all known copies are from photographs of surviving T-shirts.