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Before she would go on to make a movie with executive producer Judd Apatow, Amy Schumer appeared on two episodes of "Girls" as Shiri Appleby's overprotective friend Angie, best remembered for her hilariously scathing assessment of Hannah's appearance: "Did you leave in a rush?"

In Season 2, "Girls" sent Jessa and Hannah to upstate New York to visit Jessa's absentee father, played by a shaggy Ben Mendelsohn.

Chris O'Dowd came into "Girls" at a particularly low point in Jessa's life, and after a failed threesome attempt with Marnie, married the self-destructive Girl on a whim. It didn't end well for him.

Seen as a direct answer to criticisms of the show's predominantly white cast, Donald Glover showed up in the Season 2 premiere as a one-and-done love interest of Hannah's.

After her breakout in "Like Crazy," and before her Oscar nomination for "The Theory of Everything," Felicity Jones guest starred in a Season 3 episode as the daughter of Jessa's much older, recovering-addict boyfriend.

Gillian Jacobs showed up on "Girls" in the weeks Hannah was in Iowa and immediately snagged Adam, leading to what ended up becoming their final breakup.

Jenny Slate made a memorable appearance as Tally, Hannah's old classmate who's gone on to find fame and fortune as a blogger and author, as a not-so-veiled avatar for the real life Dunham.

A lesson about the suddenness of life and death could not have been as poignant without the arrival of June Squibb, fresh off an Oscar nomination for "Nebraska," as Hannah's grandmother.

In one of the show's most iconic episodes, Patrick Wilson deftly handled a two-hander with Dunham in which Hannah stumbles across a handsome, kind stranger and spends a perfect, romantic day with him. Ahh the stuff fantasies are made of.

In a rare instance of a star showing up on "Girls" and playing themselves, Patti LuPone had a memorable turn as Hannah tried to interview her for a magazine piece.

Marnie might as well be looking into a mirror that tells the future when she sees Rita Wilson, who has figured heavily into the final season as Marnie's mother, still partying, still self-absorbed, still pretty pathetic.

Shiri Appleby showed up for a few episodes to play Adam's first girlfriend after Hannah, but it all ended badly in a controversial scene that blurred the lines of sexual consent.

Before "Pitch Perfect," Skylar Astin showed up on the first season of "Girls" to play an old classmate of Shosh's, who almost took her virginity.

"Girls" is a show full of frequently detestable characters, but Zachary Quinto's toothbrush-chewing Ace was the actual worst, existing only to break up Adam and Mimi-Rose and show that maybe the central four characters aren't that bad after all.

In a perfect funhouse mirror of the Patrick Wilson episode, Matthew Rhys played a very different type of man to lure Hannah to his apartment, in one of the series' strongest bottle episodes.

Riz Ahmed's character seemed like a fun out-of-town fling for Hannah in "Girls" final season, but he became so much more when she realized she was pregnant from their one night stand.