Harry Houdini named himself after a famous French magician named Robert-Houdin - but today Houdini is far more famous. Are there other examples of this happening.
Note: this has to be a self-given name - Martin Luther King, Jr. is more famous than his father, but that doesn’t count!
Engelbert Humperdinck is the first one to come to mind for me; the singer is starting to fade from memory, but I think he’s still more famous than the German composer whose name he stole.
Joyce Penelope Wilhelmina Frankenberg changed her name to that of one of Henry VIII’s queens. I’m not sure which Jane Seymour is more famous these days, but during the run of Dr. Quinn, Medicine Woman, I’m pretty sure the modern actress was more famous in America.
Tom Jones was a singer under his birth name (Thomas Jones Woodward) but after the 1963 film he adopted the stage name Tom Jones. While the film and the novel it was based on isn’t forgotten, I suspect most people would think of the singer first.
This probably doesn’t count either, but the late Tupac Shakur, born Lesane Parish Crooks, was renamed at age 1 in honor of the 18th-c. Peruvian neo-Incan rebel leader Túpac Amaru II. I’m pretty sure the rapper was and even still is much better known than his namesake.
Another mom-renaming that stuck: Calvin Cordozar Broadus Jr. was nicknamed “Snoopy” after the Peanuts cartoon character he loved, and he kept it in his stage name Snoop Dogg. Now, I doubt that the rapper is actually more famous than the original Snoopy, but I’m sure there are a lot of fans who are more familiar with the former than the latter.
And another famous rapper, born Stanley Kirk Burrell, was nicknamed “Hammer” in his teens by the Oakland Athletics players he worked with, because he was thought to resemble renowned right fielder Hank Aaron (“Hammerin’ Hank” or “The Hammer”). I expect nowadays MC Hammer is better known than Hank Aaron.