Season 4 of Rick & Morty has finally debuted nearly two and a half years after season 3 came to a conclusion and the two titular characters have picked up right where they left off, taking numerous sci-fi inspired adventures and running into countless other crazy creatures across the infinite number of universes.

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There may still be five episodes left in season 4, but there have already been numerous guest stars throughout the first five episodes falling right in line with the previous Rick & Morty seasons which were abundant with celebrity cameos - and here's our list of the 10 best that have appeared throughout the entire series.

Every Community Guest Star

Dan Harmon may have found international success with Rick & Morty, but die-hard fans of the shows creator know that he also created the comedy Community, a sitcom centered around a group of misfit students at a community college.

Fans of the show have noticed several Community actors frequently popping up in Rick & Morty episodes, with key cast members such as Joel McHale, Jim Rash, Gillian Jacobs, and John Oliver having all made guest appearances throughout the years. That said, we're still waiting for Donald Glover, Alison Brie, Yvette-Nicole Brown, Ken Jeong, and Danny Pudi to make appearances (probably can't get Chevy).

Keegan-Michael Key & Jordan Peele

While it might be a cartoon, Rick & Morty is undoubtedly a comedy so it's only natural that the show might bring in some guest stars who have experience with comedic television. Enter: Key & Peele.

The comedy-duo who had their own show on Comedy Central from 2012-2015 have taken the entertainment world by storm in the past decade and have popped up in dozens of movies and shows - including the season 2 premiere where they played 5th Dimension Testicle Monsters (you read that right). This entire episode was bizarre and Key & Peele were the only comedians who could've helped pull it off.

Alfred Molina

Let's just say that you don't pay with money (followed by creepy, undertone cackle). Alfred Molina may not be the most recognizable celebrity on this list, but that didn't stop the actor's cameo from being hilarious as his character, The Devil, clashes with Rick over a variety of cursed items that he sells in an antique shop.

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One of the few guest stars from the first season, Molina's character is usually the smartest person in the room (he is The Devil, after all) and thoroughly enjoys getting the better of people - until Rick comes along and beats him at his own game.

Taika Waititi

If you haven't had the chance to watch any of season 4 yet, we'd highly recommend it - and not just because of some of the amazing guest star cameo's the season has already had, including acclaimed director Taika Waititi. The filmmaker who gained international attention after his smash-hit, Thor: Ragnarok, plays an alien named Glootie who has an incredibly keen interest in getting somebody to help him develop an app.

However, Rick tattoos on the alien's head that nobody should help him develop the app, which (of course) prompts Jerry to start helping Glootie immediately. We won't give away the episode (there are actually multiple other guest stars in it) but we will recommend it.

Danny Trejo

"Pickle Rick" is one of the most well-known episodes of the entire series (rightfully so) and it has two guest-stars that appear on this list, the first of which is Danny Trejo.

The actor plays an assassin named Jaguar, tasked with killing the pickle version of Rick when he accidentally breaks into a secure compound. This entire episode was ridiculous as it was brilliant, and the addition of Danny Trejo made it even better (especially with lines like, "this can only end with one of us dead - and I have never died,").

Werner Herzog

shrimply pibbles

This celebrity-cameo was arguably the most stunning of the entire series as world-renowned director, Werner Herzog, made a brief appearance in the season two inter-dimensional cable episode. Herzog's presence wasn't necessarily the shocking part (he's made several cameo appearances in shows and films throughout the years) but rather his dialogue was.

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The episode's subplot follows Jerry as it's found out his penis would serve as a perfect heart replacement for the most important person in the entire universe - when Jerry, understandably, has doubts about removing his genitalia, Herzog's character steps in to inform the other aliens how important penises are to the human culture (seriously, none of that was a joke).

Stephen Colbert

What happens when the most intelligent being in the universe creates his own microverse and accidentally creates a being just as smart as himself? You get Stephen Colbert to voice him, that's what.

In this season 2 episode, Stephen Colbert voices Zeep Xanflorp, the smartest being in a universe that Rick created as a hover-car-battery who doesn't admire Rick the way the rest of his race does. This starts to antagonize Rick (he did create Zeep, after all) to the point where the two geniuses end up stranded in Zeep's very own microverse. Peace among worlds, Rick - at least until your battery runs out.

Elon Musk

Again, if you haven't checked out any of season 4, we highly recommend it. In episode 3 of the most recent season, Elon Musk makes a guest appearance as basically himself, only there's one small difference - his name is Elon Tusk and he has wart-hog tusks sticking out of his mouth.

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The best part about this cameo is that the tiny change wasn't really necessary as Elon played virtually no part in the outcome of the story - he was literally there just for Rick & Morty to use clever word-play with his last name. Again, we won't give any of the episode's premise away, but Elon is basically just in this episode to be Elon - and we loved it.

Nathan Fillion

rick and morty nathan fillion

Don't worry, this isn't an April Fools joke. The season 3 premiere of Rick & Morty was one of the most well-thought-out episodes in television history by not only debuting on April Fool's Day (so most people didn't believe that it was actually happening) but also playing in a repeated cycle (thus making it seem like the episode was on an endless loop thanks to Rick's opening line).

What made it even better was Nathan Fillion voicing the character of Cornvelious Daniel, a Galactic Federation Agent tasked with retrieving the equation to inter-dimensional travel from Rick's mind. He might not have succeeded in obtaining the formula (come on, he was never gonna out-smart Rick) but he did succeed in making audiences keel over laughing.

Susan Sarandon

It certainly wasn't a traditional Rick & Morty cameo, but maybe that's what makes it the most special. Nearly every celebrity that has guest-starred on the show has played the part of some sort of weird alien or creature from another dimension. But when it came to Susan Sarandon, she got to play the character of Dr. Wong, a family therapist that the Smith's go to after Jerry and Beth split up.

The cameo occurs during the coveted "Pickle Rick" episode and shows Sarandon playing the most realistic, and functional, human that the series has ever introduced. Dr. Wong takes the top spot on our list, though, mainly for her prophetic monologue at the end that shockingly seems to put Rick in his place (for about a second).

NEXT: Rick & Morty: 10 Most Hated Supporting Characters Of All Time