Chris Shepperd in Nintendo Power. Whenever they need an image of somebody in a bad situation, they always use Chris Shepperd. According to NP, he also broke their only time machine. To a slightly lesser extent, there's Steve Thomason, who is jokingly accused of trying to turn Nintendo Power into Sega Visions. He also happens to be the one reviewing most fitness games, despite him openly expressing that he has trouble doing even 10 push-ups. To an even lesser extent, there's Justin Cheng, who received some of this in a few issues following his joining. However, this has diminished incredibly.
Before Shepperd, there was "Nester." The creation of former Nintendo fan club president Howard Phillips, Nester's sole purpose in the comic strip "Howard and Nester" was to claim to be a know-it-all gamer who ultimately would be Hoist by His Own Petard while the comic version Phillips revealed the true secret to whatever Game Nester was involved in (This was back when Nintendo Power was more devoted to providing hints and guides to games instead of reviews).
Guy Haley from White Dwarf was one of these, due to his horrible luck. His Guard army once played an entire game of Warhammer 40,000 without killing a single enemy; his Orc warband in the studio campaign of The Lord of the Rings ended up being led by a one-armed, one-legged orc with a chest problem called Ugbrag the Unlucky and he was mocked constantly for a TV appearance meny years before. He was the Editor for some of this period, but was still Butt Monkey, and at one point attempted to console himself on a particularly bad result.
The magazine's internal campaigns also develop this a lot, as someone with no army — boosting victories is likely to continue to lose.