Fighters that won a title, but lost it in the first defense? Couple come to mind. Iran Barkley - over Hearns Buster Douglas - over Tyson Frank Bruno - over McCall Jack Sharkey - over schmeling
One of the most famous ones would be Moorer winning the lineal heavyweight title from Holyfield and then getting iced by Foreman in his first defence.
Leon Spinks - HW champ of the world. Duran capturing the WBC WW title from a lot of people's 2nd best WW so far.
Billy Backus, cut eye winner over Napoles. Turpin v Sugar Ray Basilio v Sugar Downes v Pender Graziano v Zale
Tomas Molinares-Marlon Starling The result was changed to a no decision but Molinares was recognized as champ by the WBA. He suffered from depression and was knocked out in 2 subsequent fights and retired. Starling scored arguably his best victory by completedly destroying Honeyghan in his next bout. The post fight interview was a classic. This content is protected
Always remember that stretch in the '80s with the WBC flyweight title where it just passed from one to another. Prudencio Cardona to Freddie Castillo to Eloncio Mercedes to Charlie Magri to Frank Cedeno to Koji Kobayashi. With all 6 losing the title in their first defense.
The great Shinji Takehara deserves a shout out. Defeats ATG Jorge Castro then mysteriously "loses" to Joppy and retires with a bundle of cash.
Boxing is loaded with them. Aaron Davis scored a brutal knockout win over Mark Breland to win the WBA welter title then lost it to Meldrick Taylor. Think he had a couple of non-title fight wins in between though.