4. Billy Conn: 64-11-1 (15) – .197 knockout percentage

Although fiery outside the ring, Conn was the consummate boxer inside it. Turning pro at 16, Conn lost six of his first 14 fights but as he matured physically so did his skills – if not his power. He developed a stiletto sharp jab that stabbed opponents time and again, springy mobility in both directions and power shots that stung but didn’t stop. When the going got tough, Conn’s rough-and-tumble Pittsburgh upbringing provided more than enough steel to handle it.

Following his sputtering start, Conn righted himself and seldom looked back. He went 27-0-1 in his next 28 fights, defeating the likes of Fritzie Zivic, Vince Dundee, Babe Risko and Teddy Yarosz, all by decision. Losses to Young Corbett III and Solly Krieger were temporary roadblocks but Conn subsequently avenged those defeats. After running off another win string whose victims included Krieger, bomber Ray Actis and Fred Apostoli (twice), Conn won the world light heavyweight title by out-pointing southpaw Melio Bettina at Madison Square Garden.

Conn defended the belt only three times – against Bettina and Lesnevich twice – because he always had an eye toward the heavyweight championship and its owner Joe Louis. While still weighing near or below the light heavyweight championship limit, he out-boxed Bob Pastor (KO 13), Al McCoy (W 10) and Lee Savold (W 12) en route to the showdown against “The Brown Bomber.”

Conn’s quickness befuddled Louis for 11 rounds but once Conn shook the champion with a hook in round 12 the idea of not just winning the title but doing so by knockout  poisoned his mind.

“I couldn’t knock out anybody,” Conn said in 1987. “And I tried to knock out Joe Louis.”

We all know what happened: Following an early surge in the 13th Louis cracked two rights to the jaw that stopped the upstart challenger with just two seconds remaining.

Though the loss would define how most people perceived his career, his body of work – especially at 175 – cements him as a true great. His best post-Louis victory was a 10-round decision over reigning middleweight king Tony Zale in a catchweight bout. Given his low knockout percentage, it is noteworthy that Conn ended his career with two straight wins inside the distance.