Ben Askren
Askren built up a strong reputation during his time as champion with ONE Championship in Singapore. The American fighter had a strong wrestling base and he used this to dominate his opponents. He joined the UFC as a veteran with mixed results. But he talked his way into a clash with Jorge Masvidal that proved to be career-defining.
At the start of the bout, he moved forward with his head down as he attempted to shoot for a takedown. However, Masvidal predicted this move and instantly came forward with a brutal flying knee. It was the fastest knockout in UFC history and Askren’s career never truly recovered from the moment (via TalkSport).