I hate these kind of topics BUT we can't ignore them as they are part of the sport... OK here goes...

Off the top of my head the more known names that come to mind are: Alan Minter, Lupe Pintor, Barry McGuigan, Marlon Starling, Max Baer, Primo Carnera, Gabriel Ruelas, SRR, Fernando Montiel, Joe Bugner have all been in fatal fights.
Also Jesus Chavez and Ricky Quiles.

Also Ultimino Ramos has fataly been in 2 bouts where his opponents passed away.