Robert Perry Lillis (born June 2, 1930) is an American former infielder, manager, coach and scout in Major League Baseball (MLB).

Over his ten-year MLB career, Lillis appeared in 817 games and batted .236 with three home runs; his 549 hits included 68 doubles and nine triples.

After scouting and player development posts with Houston from 1968 to 1972, Lillis returned to the Astro coaching staff in 1973 and served under managers Leo Durocher, Preston Gómez and Bill Virdon.

Houston never climbed above second place, however, and even though Lillis compiled a winning 276–261 (.514) record during that period, he was replaced by Hal Lanier at the close of the 1985 campaign.

Lillis then joined the coaching staff of a former Dodger teammate, Roger Craig, with the San Francisco Giants, and remained with the team for eleven years (through 1996).