6 - Mike Tyson vs Larry Sims
Source: @BreaknNews
Win 6–0 Larry Sims KO 3 (6), 2:04 Jul 19, 1985 19 years, 19 days Mid-Hudson Civic Center, Poughkeepsie, New York, U.S. There is no know video footage of this fight. It is considered by some the "Missing Fight" etc.