Kevin Sussman

He worked at a real comic book store in New York before he played one on TV. When The Big Bang Theory came around, Sussman originally auditioned for Barry Kripke, then won the Howard Wolowitz role before Ugly Betty obligations forced him out. Chuck Lorre called him back specifically for Stuart two years later. In a third-season scene, he improvised muttering 'I love you' under his breath as Penny walked away, and the writers built the character around it. The improvised line outlasted the original plan for his entire arc.

Sixteen years after first showing up in The Big Bang Theory, Sussman gets the lead. HBO picked up Stuart Fails to Save the Universe, a ten-episode spin-off where his character accidentally triggers multiverse collapse and has to fix it. Written by Chuck Lorre, Bill Prady, and Zak Penn, it reunites him with Lauren Lapkus, Brian Posehn, and John Ross Bowie. Whether the deadpan loser energy translates to carrying a show on his own is still the open question.

Sussman and John Ross Bowie (Barry Kripke) were friends and writing partners before Sussman joined Big Bang Theory. In 2013 they sold Dark Minions, a stop-motion animated Amazon pilot, together. The comic book store background wasn't a casting gimmick: he actually worked at one in New York while auditioning and doing commercials during the dot-com era. He's also reportedly almost completely absent from social media, which, for someone whose character is defined by perpetual failure, tracks.