The greatest athlete to wear #90 is star football defensive lineman Julius Peppers. I chose Peppers over a number of other football players who were pretty good but not great- Neil Smith, Jevon Kearse, Alonzo Spellman, Larry Brooks, Ezra Johnson and George Webster a hockey player Joe Juneau and one of the early big men in college basketball Bob Kurland.
During his career with the Carolina Panthers and the Chicago Bears Peppers has been an All-Pro 8 times. He was also Defensive Rookie of the Year in 2002 and NFC Defensive Player of the Year in 2004. He was a member of the 2000 All-Decade Team. He has had 111.5 sacks during his career. He is to me a clearcut choice to be the best athlete to ever wear #90.

thats a pretty good group for number 90.