Deanna Durbin had a wildly successful acting and recording career in the 30s and 40s, retired at age 29, married (for the third time), moved to France, and hasn’t performed since 1949.
Christa McAuliffe
I see what you did there.
Srīnivāsa Rāmānujan was considered a major mathematical thinker, but died at age 32.
Nobody’s mentioned Margaret Mitchell? Her one novel made a huge splash, then she quit and died.
To be totally accurate, i.e. a good ol’ fashioned SDMB nitpick, Ken Toole (Peace Be Upon Him) actually did the exact opposite of what the OP asked about…
Okay. So, has anybody died, quit, and then made a big splash in that order? 
My money is on some military genius in the British military and it involves some paperwork…
David Hume, born in 1711, wrote his most important philosophical works between the time he was 26 and 40 (Treatise on Human Nature, 1739; Enquiry Concerning Human Understanding, 1748; Enquiry Concerning the Principles of Morals, 1751), and then kind of coasted as a public intellectual (known as “Le Bon David” in fashionable Parisian salons).
Immanuel Kant, on the other hand, born in 1724, and who was awakened from his dogmatic slumbers by Le Bon David, toiled in relative obscurity as a Privatdozent until perhaps 1781, at age 57, when the first edition of the Critique of Pure Reason came out.
Jim Brown - was still in his prime and already the greatest running back in NFL history when he retired from football at age 29.
30-odd years later, Barry Sanders was well on his way to possibly becoming the greatest running back in NFL history when he quit, also at age 29.
Just for that, here is an exceedingly literal-minded link to some people who made a big splash and then died.
TB killed John Keats at 25. It got Stephen Crane when he was 29.
Percy Bysshe Shelley was 29 when he drowned.
Sir Philip Sidney died at 31. He may have been known more as a personality than a poet at the time of his death, but he was certainly known.
Byron outlived them and made it to the ripe old age of 36.
Poets can get strange when they get old, but it would have been wonderful if these guys had even another ten or twenty years. Each of them made significant contributions to literature, influencing generations that followed, when their writing careers spanned only a few years. It’s humbling when you start to realize that you’ve outlived the masters of any field.
Mervyn Peake died before really finishing his Gormenghast trilogy.
Ann Frank was quite the noted author.
Ma ma Cass
Marvin Gay
Tupac Shakur
Gianni Versace
Jane Mansfield
Maria Falconetti.
Played in two short, silent movies and then delivered the seminal delivery of Joan of Arc - and possibly the most evocative silent film dramatic acting, ever - in La passion de Jeanne d’Arc. (1928)
Then walked off stage, never to return until her death in 1946.
All these posts and no James Dean?!
Charles Starkweather murdered 11 people on a killing spree at age 20. Executed at age 21.
His story has “inspired” at least half a dozen movies and several novels.
The wheels of justice did not grind quite so slowly in 1959.
John Belushi - broke out as one of Saturday Night Live’s Not Ready for Prime Time Players. He made several wildly popular movies, both by himself and with Dan Aykroyd. He and Aykroyd performed and recorded blues music as Jake and Elwood Blues, the Blues Brothers. His last movie, “Continental Divide,” won him critical acclaim. He died at the age of 33 in 1982 from an injection of heroin and cocaine.
Plenty of child stars, most famously Shirley Temple. Oh sure, she had a diplomatic career as an adult, but that’s not how she’s remembered.
(She just turned 84!)
Quit:
Brian Josephson - Won the Nobel prize at age 33, then descended into woo
Cat Stevens (Yusuf Islam) - Abandoned his music career at ~30 years after a religious conversion