John Ross from the University of Washington does in 4.22 seconds
The BEST 40 time in #NFLCombine History.
4.22 — John Ross.
The bar has been raised. https://t.co/ZiwKkuLwi5
— NFL Network (@nflnetwork) March 4, 2017
However the fastest in history is by Terrell Sinkfield 4.19 at the Minnesota Pro Day in 2013