Not sure what your criteria is, but I'd have to go with Jackie Robinson. From Wiki:
At Muir Tech, Robinson played several sports at the
varsity level and
lettered in four of them:
football,
basketball,
track, and
baseball.
[15] He played
shortstop and
catcher on the baseball team,
quarterback on the football team, and
guard on the basketball team. With the track and field squad, he won awards in the
broad jump. He was also a member of the
tennis team.
[23]
In 1936, Robinson won the junior boys singles championship in the annual Pacific Coast Negro Tennis Tournament and earned a place on the
Pomona annual baseball tournament all-star team, which included future
Hall of Famers Ted Williams and
Bob Lemon.
[24] In late January 1937, the
Pasadena Star-News newspaper reported that Robinson "for two years has been the outstanding athlete at Muir, starring in football, basketball, track, baseball and tennis."
[25]
Pasadena Junior College
After Muir, Robinson attended
Pasadena Junior College (PJC), where he continued his athletic career by participating in basketball, football, baseball, and track.
[26] On the football team, he played quarterback and
safety. He was a shortstop and leadoff hitter for the baseball team, and he broke school broad-jump records held by his brother Mack.
[15] As at Muir High School, most of Jackie's teammates were white.
[24] While playing football at PJC, Robinson suffered a fractured ankle, complications from which would eventually delay his deployment status while in the military.
[27][28] In 1938, he was elected to the All-Southland Junior College Team for baseball and selected as the region's Most Valuable Player.
[22][29]
UCLA and afterward
Robinson doing the long jump for UCLA
After graduating from PJC in spring 1939,
[36] Robinson enrolled at UCLA, where he became the school's first athlete to win
varsity letters in four sports: baseball, basketball, football, and track.
[37][38]
He was one of four black players on the Bruins'
1939 football team; the others were
Woody Strode,
Kenny Washington, and Ray Bartlett. Washington, Strode, and Robinson made up three of the team's four backfield players.
[39] At a time when only a few black students played mainstream college football, this made UCLA college football's most integrated team.
[40][41] They went undefeated with four ties at 6–0–4.
[42]
In
track and field, Robinson won the
1940 NCAA championship in the
long jump at 24 ft 10 1⁄4 in (7.58 m).
[43] Belying his future career, Robinson's "worst sport" at
UCLA was baseball; he hit .097 in his only season, although in his first game he went 4-for-4 and twice
stole home.
[44]
Seriously you don't know who is Danny Ainge? 
