Tony DeMarco (January 14, 1932 – October 11, 2021), born Leonardo Liotta,^[1] was an American boxer and World Welterweight Champion.^[2] Born to Sicilian immigrants from Sciacca (AG), Vincent and Giacomina, DeMarco grew up in the North End neighborhood of Boston.

DeMarco was also, for a short time, a resident of Phoenix, Arizona,^[3] where he was a business owner and where he suffered the death of his young son by way of a car-bicycle collision.

Due to the minimum age of eighteen, in order to box professionally, Liotta used the baptismal certificate of Tony DeMarco so that he could compete.^[4] DeMarco had his first professional fight when he was sixteen years old. On October 21, 1948, he knocked out Mestor Jones in one round.

DeMarco fought the top fighters in his division during the 1950s and defeated top contenders and champions like Paddy DeMarco, Teddy "Red Top" Davis, Chico Vejar, and Don Jordan. The highlight of his career came on April 1, 1955, when he scored a technical knock out (TKO) over Johnny Saxton in the 14th round of their title bout to capture the world's welterweight title.

Despite winning many bouts to become champion, he is best remembered for his two championship matches with hall of famer Carmen Basilio in 1955. Both fights were toe to toe slugfests with several ebbs and flows that kept the fans at the edges of their seats. Both fights ended in the 12th round with DeMarco suffering a TKO. In their first bout, DeMarco was the defending champion. He risked his title by taking on Basilio, who was the top ranked contender. Although Basilio prevailed, the fight was so exciting that the pair were rematched. The second fight was almost a carbon copy of the first with Basilio wearing down DeMarco, but not before a wicked DeMarco left hook had Basilio out on his feet. DeMarco was unable to capitalize on this advantage and lost the match on a 12-round TKO.

• List of welterweight boxing champions