Top 3 undefeated boxers of all time

It's damn near impossible to embark on a long and storied boxing career without ever tasting defeat.

Losing is almost a certainty, due to myriad reasons. Fighters hold on for too long. Chins weaken. Reflexes slow. Judging can run the gamut from terrible to downright corrupt.

Most of the greatest boxers of all time have red in their ledger. Muhammad Ali lost five times. Even Sugar Ray Robinson - quite possibly the finest boxer to ever lace up a pair of gloves - was on the losing end 19 times in his illustrious career.

Still, a handful of men who practiced the sweet science professionally have hung up their gloves with a spotless record.

Here is a list of the top three undefeated boxers of all time:

Floyd Mayweather Jr.

One of most technically gifted pugilists of all-time, Floyd "Money" Mayweather has fashioned a 47-0 record over an almost two-decade career, while collecting more title belts than any one man could possibly fit on his body.

The list of world champions the pound-for-pound great has conquered during his stellar career is staggering, and the defensive wizard is 24-0 in world title fights.

Of course, there's a chance Mayweather's undefeated streak crumbles at the hands of fellow world champion Manny Pacquiao at the "Fight of the Century" on May 2, in what could be the sport's last hurrah.

Rocky Marciano

One of the greatest heavyweights to ever set foot in the ring, Rocky Marciano crafted a 49-0 record over an eight-year career that included six successful title defenses.

Although "The Brockton Blockbuster" owns victories over such greats as (a decidedly shopworn) Joe Louis, Ezzard Charles and Archie Moore, Marciano was plagued by rumors that his management would pick and choose his opponents, preferring the undersized heavyweight avoid the giants of the division.

Despite the supposed gaps that exist in his record, Marciano is the only person in boxing history to hold the heavyweight title without suffering a loss or a tie, and that's borderline ridiculous.

His right hand is also responsible for this indelible image of Jersey Joe Walcott's twisted mug: 

Ricardo Lopez

Likely overlooked as one of the greatest pound-for-pound boxers of all time because of his diminutive size, Ricardo Lopez's resume is littered with defeated world champions, as he crafted an incredible 51-0-1 record over his sterling 16-year career.

"El Finito" owns victories over 10 world champions and is 25-0-1 in world title fights. His lone blemish came in the form of a tie against Rosendo Alvarez in 1998, but Lopez would go on to defeat Alvarez in their rematch later that year.

Considered the greatest strawweight to ever throw a punch, Lopez was inducted into the International Boxing Hall of Fame in 2007.

Honorable Mentions: Joe Calzaghe, Laszlo Papp, Edwin Valero, Packey McFarland