Michael Scott
Although Michael was Dunder Mifflin's top salesman for a number of years on The Office, those skills did nothing for him when he assumed the role of Regional Manager. Jim even made a graphic depicting Michael's activities at work which indicated that he spent most of his time procrastinating or wasting his employees' time. It's honestly a miracle that he managed to keep his job for so long.
Mike McLintock
One might expect the White House Press Secretary to be slightly more competent, but Veep's Mike McLintock dropped the ball so many times that it's difficult to recount them all. Despite his constant blunders, McLintock gained respect as a journalist after his run alongside Selina Meyer, eventually being promoted to lead anchor of CBS Evening News.