What do you think are the boxing records in general or for a specific weight class that are least likely to be broken?

Here's a couple I think are pretty safe
Joe Louis' 25 Consecutive Successful Title Defenses at Heavyweight

Wilfredo Benitez's youngest Champion at 17 years old

Mike Tyson youngest heavyweight champion at 20 years old

Evander Holyfield 5 time heavyweight champion

Edwin Valero's 18 consectutive 1st round KO's

I think Marciano's 49-0-0 will be beaten 9as Larry Holmes and even Nicolay Valuev have been within 1 fight of matching it), but I doubt the fighter that beats it ends his career undefeated.

Can you guys think of any others?