Life with Unix says: Co—developer of Blit bitmapped terminal.

A Research Unix Reader says: Rob Pike supplied a multiprogramming system, host-terminal communications, mouse control, and support for overlapping virtual terminals (mpx, later mux). Pike's system fostered fascinating programs by many people, of whom I shall mention only a few (v8). Pike himself built visual editors, culminating with sam (v9), which went well beyond the command capability of vi — seemingly with no more mechanism than the venerable ed. (Rob's simplifying touch is also visible in the shell, in p for paginating, and in his recasting of Chesson's remote execution software, all in v8.)