Kids, I'm going to tell you an incredible story, the story of how I met all these super famous people before I met your mother.
How I Met Your Mother ran from 2005 until 2014. It gained more and more popularity with each legen--wait for it--dary season. The romantic sitcom consistently added more inside jokes with its audience, creating a large and loyal fanbase.
As with most TV shows, as they became more and more popular, bigger named celebrities started popping up, either for guest appearances, cameos, or even recurring parts.
Some of these celebrity performances become more than just "Hey, look, it's a famous person!" Some provide lots of humour, depth, and character growth for the show, proving their worth as more than simple cameos.
And others are just plain hilarious, without even doing all that much.
10. Laura Prepon
Laura Prepon bounced from one iconic sitcom to another.
After starring as Donna Pinciotti in all 200 episodes of That '70s show, Prepon popped up for a few episodes in How I Met Your Mother Season 4 as Karen, Ted's college girlfriend.
Lily and Marshall HATE Karen, with Marshall stating that if they got back together it would be the fourth worst thing in the world, and it's easy to see why. Prepon plays Karen as an obnoxious high brow know it all who constantly cheats on Ted. Somehow, Ted is the only one who can't see that Karen is the worst, making her cameo all the funnier.
Prepon returns as Karen for a quick appearance in Season 5's Say Cheese, where she ruins Marshall and Lily's Paresian Vacation and solidfies herself as Ted's worst ex, including the one who left him at the altar.
Richard C. Kraus (Richie to pretty much everyone) is an American college student and world record holder for most views of the 2015 film Ant-Man. He has ambitions to someday be a screenwriter, actor, and not tired.