Have written here and here about how a series supporting character could have been turned into a lead role, when it came time to either reconfigure or cancel the series. Another example: Oliver Platt in Huff, which starred Hank Azaria, and where Platt played Russell Tupper, an lawyer with…challenges. Series lasting two seasons, 2004-2006. As noted by Paul Brownfield in “Analyzing the stuff of ‘Huff’” (Los Angeles Times, November 5, 2004):
It’s Oliver Platt as Huff’s power lawyer and friend, Russell Tupper, who steals the show repeatedly, providing comic — and dramatic — relief. He’s the show’s anarchic life force, what can make it special.
When first we see him, he’s having lunch with Huff, ordering a second martini and explaining how a client’s sexual-harassment case is based on the fact that she wasn’t harassed in the workplace and should have been. Unlike Huff’s midlife crisis, Russell’s involves a lot of drugs, booze and sex — with hookers, with waitresses, with the chicks who deliver his new plasma TV. Really, it’s a pretty enlightened potpourri.
Platt is an actor who’s long seemed better than the material he gets. On “Huff,” it feels a bit like he’s wandered in from another movie, but then Platt has always had the barrel-chested look and malleable facial qualities of a comedic actor from the 1940s. He’s easily the best thing about the series’ initial episodes, repeatedly hoisting the show on his shoulders and taking it to truly risky places.
Or here, at 25, 33 and 42 minutes in: