For those that don't know, groff's ancestor "roff" is very closely tied to UNIX's origin story. roff itself had it's own antecedent called RUNOFF (whence the name) on Multics. roff was basically UNIX's first "killer app" and was used to typeset patent applications by the division of Bell Labs that handled that sort of thing. It legitimized the further development of UNIX.

Groff seems to be somewhat supplanted by mandoc these days, at least on the BSDs.