There is much debate on who holds the fastest 40 time. Now, the 40 yard dash or simply "The 40" began with NFL Scouts. Therefore, I will not mention any olympic sprinters in my answer. Moving on, supposedly, Willie Gault of the Bears back in the 80's ran less than 4.1. He was termed the Fastest Man in the NFL during his tenure. There are many others that have recorded less than 4.2 and that includes, Bo Jackson, Deion Sanders, Joey Galloway, and D'Angelo Hall (rubber track).