Thomas James Lawless (born December 19, 1956 in Erie, Pennsylvania) was a Major League Baseball player between 1982 and 1990, playing for the Cincinnati Reds, Montreal Expos, St. Louis Cardinals, and Toronto Blue Jays.

Although just a fringe, part-time player throughout his career, Lawless was involved in a number of dramatic and historic moments. Lawless became famous in 1984 when he became the only player ever traded for the great Pete Rose. Lawless, who only hit two regular-season home runs his entire career, is also remembered for his dramatic game-winning home run in Game 4 of the 1987 World Series (he had hit .080 in 25 at bats during the regular season.) "When it went over the wall, I thought" Lawless told reporters at the time. "'Holy cow, it went out.' The ball went out and I went blank for a second. It went out. I don't remember flipping the bat."

On May 10, 1989, while with the Toronto Blue Jays, Lawless' ninth inning single broke up a no-hit bid by Mark Langston of the Seattle Mariners.