When a television show reaches a certain level in the cultural consciousness, it starts to expand. Everything gets bigger: the seasonal arcs, the cast, the budget, and the opportunities to have a famous fan show up for a scene or two. Most big shows, no matter the genre, have their share of celebrity cameos and guest stars. It’s gimmicky and more than a little goofy, but oftentimes it’s a fun way for a show to let a well-known fan who’s been begging for a guest spot give them some free extra clout, or simply feature some celebs that the writers know the viewers will get a kick out of seeing within that world.

Some of these cameo roles, however, are more jarring than others. So jarring, in fact, that that one celeb appearance may be the only thing about the episode that anyone talks about afterward. We all remember where we were when a certain Irish pop singer showed up on a certain blockbuster fantasy show (more on that below), but barely anyone remembers what actually happened in that episode.

These weird cameos and guest spots can be fun or they can be annoying, showing the gimmick a little too much while distracting from the plot of the actual episode. Even a cameo ought to serve the story in some way, but sometimes the cameo is the only thing anyone’s paying attention to. These are the most unforgettable celebrity cameos and guest spots in beloved TV shows, memorable mainly for how obviously they stood out from everything else.

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