Personally two records I can never see being broken is Wilfred Benitez being 17 winning a world title and Willie Peps two unbeaten streaks of at least 62 fights.
None of them are unbeatable, that's how records work. The ones I think are hardest to beat are... Amount of fights, set by Len Wickwar, at 470
Packey McFarland's 103 fights unbeaten Len Wickwar's 470 professional fights (340 wins + 87 losses + 42 draws + 1 NC) Peter Maher's 50 1st round knockouts Tommy Burns' shortest heavyweight champion (5'7) Rocky Marciano's shortest hw champion reach (68") For the foreseeable future these are completely unbeatable due to modern boxing customs 2 I'd like to add in, they aren't impossible to beat but I find it highly unlikely they will be: Rocky Marciano's 49-0-0 at heavyweight Joe Louis' 25 consecutive title defenses
Gawd knows what we're going to do if Wilder breaks Marciano s record! He's edging closer, think he's got about 6 wins to equal Rock. We'll have to put Wilder on the same level as The legendary Marciano..
Kristian Laight's 300 fights without EVER winning a single one inside the distance. Kristian Laight's 279 defeats Harry Greb's 45 straight wins in a single calendar year (1919). Henry Armstrong's 12 world title fights in one calendar year (1939) Henry Armstrongs 5 world title fights in one calendar month (Oct. 1939) Kid Azteca being active for 33 consecutive years (1929-1961) Jack Britton's streak of 342 consecutive fights without a single knockout defeat.
That Korean female boxer who won the title in her first pro fight. Can still be matched in men's though, obviously. Edit: her name is Choi Hyunmi.
I have just counted his 1919 bouts in the last edition (1986-1987) of The Ring Record Book - and like BoxRec, they list 45 fights.