Hall of Fame: Yes
Career highlights: National League MVP 1935, runner up 1937. Six All-Star teams (the game was created midway through his career). His famous "Homer in the Gloamin'" was a pivotal moment in the 1938 pennant race. Regular catcher for four World Series teams, none of which won — he was, after all, a Cub.
Career slash line: .297/.370/.489
Game caught after age 30 season: 958. Age in last season as regular catcher: 36 or 38, depending on what standard you apply. Win shares after age 30 season: 164. Win shares after age 33 season: 93.
It's relatively easy to find possible reasons why modern stand-out catchers last longer than their earlier counterparts: They're in better condition, sports medicine is better, better equipment, PED use ... and none of them quite explain Gabby Hartnett, who remained a productive player deep into his 30s.
Of the 14 catchers in this pool, only Carlton Fisk caught more games after age 30 than Hartnett. (Ivan Rodriguez could catch him this season.) Only Fisk and Yogi Berra have had more win shares after age 30, and a good portion of Berra's came as an outfielder. Only Fisk had more win shares after age 33.
It is worth noting, however, that Harnett only twice caught as many as 130 games in a season. He missed almost all of the 1929 season, his age 28 season (caught one game). Whether by design or happenstance, he was not abused as a young catcher.
The story behind the photo above of Hartnett and gangster Al Capone: The mob boss took his son to a charity exhibition game between the Cubs and White Sox, and Hartnett, a gregarious sort, agreed to autograph a ball. When the photo appeared in the paper, Commissioner Landis called Harnett in — Landis operated out of Chicago — and ordered him not to do that any more. Hartnett replied: "Judge, if that's your rule, it's OK by me. But I'm not explaining it to him. The next time you see him, YOU explain it to him."