Eugene Michael Guarilia (born September 13, 1937) is a retired American basketball player.

He attended Holy Rosary High School. Guarilia played freshman basketball for Potomac State College, a junior college in Keyser, West Virginia. He established a State Conference freshman record by scoring 595 points in 1953.

A 6'5" (1.96 m) forward Guarilia played for the George Washington University varsity basketball team beginning in the 1956-1957 season. He took the place of All-America Joe Holup who went on to play for the Syracuse Nationals. In February 1957 he was averaging 17.1 points per game and was #6 in the NCAA in rebounding. In the twenty games he had played, Guarilia had snatched 353 rebounds. He was selected to the all Southern Conference basketball team in February 1958.

Guarilia was selected by the Boston Celtics in the second round of the 1959 NBA Draft. Guarilia appeared in 129 games for the Celtics over four seasons (1959-1963), averaging 3.2 points and 2.3 rebounds per game. He earned four NBA championship rings in his brief career.

In December 1959 Boston placed Guarilia on its farm out list to trim their roster to the required 10 player limit. Though officially off the Celtics' roster, he remained in Boston to be available if other players were injured. Red Auerbach considered rotating Guarilia on the active list with one of the other Celtics rookies, like John Richter. The coach said that this move could be done in accordance with NBA rules.

Guarilia was particularly effective in Boston's 1961-62 NBA championship victory over the Los Angeles Lakers. In the final moments of regulation time, in the decisive seventh game, he stopped Elgin Baylor. The Celtics went on to win the game in overtime.

A new NBA rule allowed Guarilia to become the 11th man on the Boston roster in the (1962-63) NBA Championship versus the Lakers. On September 25, 1963 the Celtics placed Guarilia on waivers to reduce their playing squad to 16 players.