Steve Carell portrayed Michael Scott on The Office but the character was nearly played by Bob Odenkirk instead. Despite leaving the sitcom in the show's seventh season, Carell is still considered the face of the series. The Office could have been a lot different if it wasn't for last-minute casting changes.
The Regional Manager of Dunder Mifflin's Scranton branch was the central character of The Office. Carell played the character from 2005 until he left the series in 2010 to focus on his movie career. He perfectly embodied the character of Michael during his stint on the award-winning comedy. It's hard to imagine the incompetent, yet hilarious, boss being played by anyone else, but that was almost a reality.
The characters in The Office were an adaption of the original British version of the series. Paul Giamatti was actually suggested for the role of Michael Scott but the actor declined the audition. Other names that were interested included Hank Azaria, Martin Short, and Bob Odenkirk. Carell was considered for the role but his availability hindered his chance so Odenkirk was chosen to play Michael.
Odenkirk was a member of the cast when the series was presented to NBC. When The Office was being cast, Carell had interest but he was already committed to star in another NBC series, Come to Papa. The sitcom only aired four episodes before being canceled which opened up Carell's availability. He quickly jumped back on to the Michael role. Carell had never seen the British version of The Office but that actually helped him acquire the role as the writers didn't want him to be a carbon copy of Ricky Gervais' David Brent.
Odenkirk may have lost out on the lead role but that wouldn't be the end of his relationship with The Office. In the sixteenth episode of the final season, Odenkirk appeared in a small role that poked fun at his short stint as the manager. The episode, titled "Moving On," featured Pam (Jenna Fischer) interviewing for a job in Philadelphia so she could possibly be closer to Jim (John Krasinski). The boss that she interviewed with was played by Odenkirk and his demeanor gave Pam total deja-vu. The character, Mark, was a carbon-copy of Michael Scott as they had the same sense of humor and behavior.
It's tough to say whether or not Odenkirk would have had as much success as Carell if he stayed on with The Office. The casting change certainly didn't hurt Odenkirk's career in any way. If Odenkirk would have kept his role as Michael, he wouldn't have been available to play Saul Goodman on Breaking Bad, meaning the actor also would have never received the spinoff series, Better Call Saul. It seems like both Carell and Odenkirk (and their fans) benefited from the Michael Scott casting decision in the long run.