The Marvel Cinematic Universe balances its heavy drama and its wild action scenes with hysterical comedy and witty humor, which has been a part of the MCU ever since Tony Stark's one-liners in 2008's Iron Man. Plenty of Avengers have a great sense of humor, most of all the misfits of the Guardians of the Galaxy.
The Guardians of the Galaxy have always been a wacky bunch, and that's practically their calling card in the MCU. Those movies are truly stylish with cartoony outer space adventures, groovy 1970s rock songs, pop culture references, and plenty of lighthearted jokes and witty banter to keep audiences laughing until the final credits. That said, some Guardians are funnier than others, and some of them don't even mean to be funny – but still are.
10 Gamora
Understandably, the elite alien assassin Gamora takes herself seriously and almost never makes any jokes, and she rarely laughs at anyone else's jokes, either. She's had a tough life as Thanos' foster daughter, and she's too preoccupied with personal drama to goof off.
That said, Gamora slowly warmed up to her fellow Guardians and learned to at least put up with their zany antics if there aren't any bigger issues to deal with. In Endgame, Gamora humorously looked at Peter Quill in disbelief, openly wondering "That's my future boyfriend?" As Nebula put it, the choices were between Peter and a tree.
9 Nebula
Gamora's foster sister Nebula nursed a serious grudge, determined to finally defeat Gamora in a duel and prove herself to Thanos. Like Gamora, Nebula takes herself seriously, but she might also say or do funny things without realizing it.
Nebula once spat out a fruit because it wasn't ripe, and in a subtle moment in Endgame, she humorously struggled to figure out how chopsticks work. She also dryly confirmed that Star-Lord is a total idiot when she and War Machine watched Star-Lord dancing and singing by himself on Morag.
8 Yondu Udonta
The Ravager boss Yondu Udonta would rather intimidate or manipulate someone than earn their loyalty with humor and charisma, though he's still capable of cracking jokes. In the first Guardians movie, for example, he humorously took it in stride when Peter swapped the Power Stone for a little doll.
In Guardians 2, Yondu was scary at first, then showed his humorous side. He amusingly criticized Groot for retrieving the wrong items over and over, and most famously of all, he declared "I'm Mary Poppins, y'all!" when Peter assured him that Mary Poppins is pretty cool.
7 Mantis
The charming alien Mantis appeared in 2017's Guardians of the Galaxy Vol. 2 in the MCU's third phase. She was introduced as Ego's personal assistant and companion, often called upon to soothe his emotions so he can sleep.
Mantis was a timid and unassertive alien who would make jokes at her own expense, which Gamora didn't approve if. Over time, Mantis became more confident and started cracking even better jokes, such as quipping in Infinity War that she and the Guardians will "kick names, take ass."
6 Kraglin Obfonteri
At first, Kraglin was a minor antagonist of sorts, working for Yondu in Guardians, but then he turned on the petty villain Taserface to help Yondu, his true captain, escape alive. Kraglin had a much bigger role in Vol. 2, such as his joke to Nebula about her buying a hat or jewelry with her reward money.
Kraglin had a few serious scenes, mostly pertaining to Yondu, but he also knew how to goof off and enjoy life in outer space. In a mid-credits scene, for example, Kraglin fumbled with Yondu's whistle-controlled arrow and accidentally hit Drax with it, then nervously walked away.
5 Rocket Raccoon
Rocket Raccoon is a total rogue who only lives for his own sake, and he uses harsh humor to deflect all the serious topics. He may be prickly on the outside, but he still cares about his fellow Guardians and might liven things up with banter or witty comments.
Rocket was the one who burst out laughing at Taserface's name, and suggested and even stranger name. Rocket also amused MCU fans with his habit of stealing prosthetic body parts just because he can, and his interaction with baby Groot concerning their improvised explosive device was hysterical.
4 Drax The Destroyer
Drax the Destroyer is a brute-force Guadian who acts first and thinks never, which often makes him funny rather than intimidating. Drax also takes things literally, claiming that no joke could go over his head because he could catch it with his sharp reflexes.
Drax amuses MCU fans with his crude, blunt questions and observations, and he often acts totally clueless, too. His weirdest joke was in Infinity War, when he very falsely claimed that he could eat snacks so slowly, he would be invisible to the naked eye.
3 Star-Lord
Peter Quill was raised by Yondu's Ravagers and assumed the title Star-Lord, though at first, no one knew that name, and Peter was so disappointed each time people failed to recognize him. Like Rocket, Star-Lord often uses humor to deflect serious issues, but not as often or as harshly.
Star-Lord also delighted MCU fans with his goofy, carefree song and dance routine on Morag, and actor Chris Pratt actually improvised his scene where Star-Lord almost dropped the orb before handing it to the Collector. Star-Lord also has amusing reactions to everything around him, including exasperated expressions and "Dude!" now and then.
2 Thor Odinson
For a brief time in the MCU's third and fourth phases, Thor Odinson was a Guardian of the Galaxy. He owed them everything for rescuing him and helping him forge the axe Stormbreaker, but he eventually quit the Guardians to deal with Gorr the God Butcher.
Thor, despite his pretentious side, has always been one of the MCU's best jokers, from his obliviousness to Earth customs and technology to his oafish mishaps and his one-liners. He was at his funniest in Thor: Ragnarok, but he also had a few good jokes in Infinity War and Endgame despite his dire circumstances.
1 Groot
Even if he only says "I am Groot," the tree-like alien Groot is definitely the Guardians' funniest character, mostly through his actions and facial expressions. He's even amusing in combat, such as beating up Ronan's guards and then making a goofy smile as though to say "I did it!"
Groot is also humorously impulsive and daring, and some of Rocket's dialogue suggests that Groot has truly weird things on his mind. For example, he tried to defend Star-Lord having 12% of a plan by commenting that at least it's better than having 11% of a plan.