Marius Ugo Russo (July 19, 1914 – March 26, 2005) was an American starting pitcher in Major League Baseball who played for the New York Yankees from 1939 to 1943 and in 1946).

Russo, known as "the Kid From LI", played baseball for Richmond Hill High School in Queens.

In his rookie season for New York, he finished with an 8–3 record and a 2.41 earned run average in 116 innings including two shutouts and nine complete games.

His 3.09 earned run average was the best of the Yankees pitching staff and the 4th best in the American League, being surpassed only by Thornton Lee (2.37), Al Benton (2.97) and Charlie Wagner (3.07).

Russo also started and won a complete game 2–1 victory in the Yankees 1941 World Series win over the Brooklyn Dodgers.

A sore arm limited Russo to pitch only 45+1⁄3 innings in 1942, ending the season with a 4–1 record and a 2.78 earned run average in nine games (five as a starter).

Russo died of heart illness in a hospital near his home in Fort Myers, Florida, at 90 years of age.