Tho I dont think its the most powerful jab ever (that would either go to Quartey or Wlad)...but if your asking about someone KOing a fighter with a jab...Buster Douglas did it early in his career.
Kelly Pavlik has a very powerful jab. He has such long arms, and when it lands, you can see on the guys face, it ****ing hurts. The first fight with Taylor, when he really started jabbing in rounf 4, you could tell Taylors reaction as he was getting tagged. He just looked discouraged, like "ow, damnt, OW, ow, **** that hurt"
I say it in every thread about great jabs (said it a few posts ago)...and it seems that the only time anyone takes notice is if the thread is in the classic section. But I will reiterate. ANY POST ABOUT GREAT JABS (HW and otherwise) that does not include Buster Douglas is severely lacking.
You all named some great names. Sonny Liston-freight train powerful jab. It wasn't fast but it was sharp. Klitchko-good jab Larry Holmes-probably the best overall I've seen in that he could throw it multiple ways and it was quick. He could throw it conventionally, he could flick it from a 3/4 extended position and most of all he had a ridiculous "up jab'. Ali-in his prime probably the best big guy who could move with his jab. Ike Quartey & Winky Wright- Both have incredible jabs Hearns-beautiful boxer and could win a fight with his jab, see the Benitez fight as an example. I'm going to throw up another person who wasn't a great fighter but when they fought I thought he won. Carl THE TRUTH WILLIAMS He totally out jabbed Larry holmes and granted larry was on the downside of his career but he totally outjabbed/outsped Larry that fight. Btw, whoever made mentioned of Ricky Hatton landing a jab on Floyd, come off that. You then said Floyd was off balance (which he was) and later in the fight, Floyd opened up his jab even better than Hatton did the entire fight. Come on.