Anybody who fought or contested over 15 rounds who isn't usually associated with the 15 round era. E.g., Holyfield going 15 when he was at cruiser despite being more associated with the 90s and his HW run where he never went beyond 12.
Orlando Canizales once fought 15 rounds against Kelvin Seabrooks. That fight was supposedly one of the very last 15 round fights before they permanently changed it to have 12 round limits.
Jorge Paez came from behind to drop Calvin Grove 3 times in the 15th round to take the title from him. I think only a couple weeks later, their sanctioning body eliminated 15-rounders.
I wouldn't normally associate Holliday with 15's but he did go 13 in a fifteen-rounder with Chim Richalds.
Mike Tyson: His fight with Tyrell Biggs was the last heavyweight title fight scheduled for 15 rounds. Of course it didn’t go the distance (and it was his only scheduled 15). Harold Brazier and Buck Smith fought 15 rounds for no title. They wanted to do it while 15-rounders were still not completely done away with so they agreed to a fight in Oklahoma (which had no commission). Went the distance, I think Brazier won but it was changed to a no contest or an exhibition retroactively iirc.
I chose a random fighter from the pre-war British era and that was George 'Panther' Purchase. If you don't know who he is, that's OK, because there were so many like him up and down the England coast plying their trade that he and others like him can get lost in the crowd. Panther had 127 fights with an unremarkable record of 77-41-8 with one no contest. Panther never fought for the world title, was never world-rated, never fought for British, Commonwealth (Empire at the time) or European honors. The best he fought for was the South African (where he was originally from) lightweight and welterweight titles as well as the British Area Welsh welterweight title (twice) all unsuccessfully. However, with the game so competitive and popular back then, Panther actually competed in 37 scheduled 15 rounders. And again, I would say his numbers were quite average with the competition of the time.