Otto Schnellbacher.
I have to give this one to the legendary two-sport star, even though he played only two season (1950 & '51) with the New York Giants.
Schnellbacher was named to the Pro Bowl as a defensive back both seasons he played with the Giants, and was All-Pro in 1951 when he led the league with 11 interceptions. Schnellbacher played for the New York Yankees of the AAFC in 1948 & '49. He was also playing professional basketball during those two seasons he was a Yankee.
I really wish I knew why Schnellbacher's career in the NFL was so short, especially since he was so dominant in his final season. Things weren't like they are now, where players hang on for the paycheck.
Wide receiver Earnest Gray wore the 83 jersey for the Giants from 1979-81 after being drafted in the second round. He caught 243 passes as a Giant for an average of 15.4 yards per catch. His best season was 1978, when he caught 78 passes for 1,139 yards and five touchdowns.