BoxRec

I've mentioned it in other threads, but David Bey beat Buster Douglas in his first fight.

Any other good ones?

Canadian Jean Claude Roy debuted on Dec. 6, 1964, with an 8-round decision over former British Empire light heavyweight champ and two-time world title challenger Yvon Durelle in Montmagny, Quebec. The brawling Durelle was 88-23-2 at the time, but couldn't figure out the southpaw Roy, who then moved up to heavyweight and retired in 1970 with a pedestrian record of 8-10 (2 KOs). His "name" losses were to George Chuvalo and Cleveland Williams ...

Jonny Carlo, KO 1 Leon Spinks.

Clinton Mitchel beat Hopkins on his debut, also worth a mention Javier duran beat jmm in his 2nd fight and omar Amaya beat arguello in his 2nd fight.

Kid Da Costa bet Ted Kid Lewis in his first (and only?) fight. Suspect his record is incomplete but it appears to have been his debut.

Bobby Dunn laid Benny Leonard out cold with a single punch in his debut. Leonard also lost his debut against a guy who was 1-1-0 and I suspect that's his crowning achievement as a pro.

Clinton Mitchell beat Hopkins in his pro debut

James Broad beat Bonecrusher in his second fight, I think. Stopped him too.

Eddie Trujillo beat Henry Armstrong in his debut

Miguel Canto lost two early fights to two debutants.

Maskaev debut against 21-0 Miroshnichenko is worth mentioning.

Depends how you look at this does it not? By "best pro win" I thought it mean "in regards to where the loser was at that time" (so a win over a debuting Hopkins wasn't a great win as it came over another debutant likewise a win over a fighter who was shot should be down rated)

How about Samart Payakaroon against former world champion Netrnoi Sor Vorasingh? (9 months removed from Netrnoi's loss to Hilario Zapata)

If he wins in November against Jason Canoy, then Hinata Maruta would deserve to be in consideration I'd assume?