Specifically, it's a rendition of the daemon from the cover of the 4.2BSD UNIX System Manager's Manual[1].

“Cover design by John Lassetter [sic], Lucasfilm, Ltd.”[2]

[1] https://archive.org/details/smm-4.2bsd/mode/1up

[2] https://archive.org/details/smm-4.2bsd/page/n1/mode/1up