Terrence is a brilliant character. He's basically a sociopath, but he gets enough Villain Episodes and Strange Bedfellows scenes that that doesn't matter, and he somehow manages to be both hilarious and terrifying, often simultaneously.
Bakura and Marik too. Is it any wonder LittleKuriboh loves to use them so much?
If abridged series characters qualify, then Sokka in Avatar: The Abridged Series deserves at least a mention. Twice the Meta, twice the Butt Monkey, four times the funny ("So he's like... Kung Fu Action Jesus?").
From Sailor Moon Abridged: Raye. She's an aggressive, shrill-voiced Satanist and pyromanic who just wants to sacrifice small animals in peace. Saddled with The Ditz as team leader, you can't help but feel bad for her when she meets her new team member, a Valley Girl: OH MY GOD THERE'S TWO OF THEM!
Goku from the same series. Whenever he's around, the episode is 10 times funnier.
Strong Bad. He's quite possibly one of the most hilarious animated characters ever, and I'm usually wary of cases where the Anti-Hero type becomes more popular than the plain, simple hero (usually leads to character bashing lobbed at said hero, etc). H* R makes it work because Strong Bad is actually funny and his instances of not being as cool as he says he is make him that much cooler. Plus, Homestar definitely works better as The Ditz than the heroic athlete so it all balances out.
Jack Bulletproof, the Cop Who Plays by All the Rules. Because police procedures are there for a reason, and anyone who manages to be this awesome while doing the most reasonable and thought-out thing in any given situation deserves a mention.
The Nostalgia Critic: So messed up...and so entertaining to watch. Also, his singing voice. Dear God, his singing voice.
OH MY GOSH, CHESTER A. BUM IS THE GREATEST CHARACTER I'VE EVER SEEN IN MY LIFE! He's deranged, stoned out of his mind, and absolutely hilarious.
Oh, Felix.Felix,Felix,Felix, where do I begin? A villain whose nature is a shocking yet satisfying twist, Felix manages to make his partner Locus look like a minor threat by comparison. He's delightfully smug, unapologetically evil, and yet surprisingly complex and nuanced when you take a closer look at him. His one major weakness just makes him more appealing, especially due to an absolutely brilliant monologue written by his creator and voice actor, which actually manages to give him a shred of humanity, without earning any sympathy.
RWBY's Pyrrha Nikos is an experienced, extremely capable fighter (she is the four-time Mistral tournament champion) and a stellar student, much like Weiss Schnee. Unlike Weiss, despite being a celebrity figure, Pyrrha is incredibly humble, polite, and willing to lend a hand to anyone who needs it, easily one of the gentlest characters in the show. She will stand up to people who she deems "atrocious", however, and will have no problem handing their asses, all four of them. Not to mention, she is a beautiful Statuesque Stunner, with piercing green eyes and red hair.
Yang Xiao Long, aka the shotgun-gauntlet wielding brute force of the eponymous team. She is such a Blood Knight that she took up being a Huntress solely to get into fights. Despite being an arrogant hothead, she has a huge heart and a strong nurturing side to her baby sister. She also has awesome hair, and woe betide any being foolish enough to lay a finger on it, be it a Grimm or a Too Dumb to Live bartender. And that's not even getting into her awesome Semblance. She cares for her teammates' well-being so much that she won't hesitate to use force to knock some sense into them when they insist on destroying themselves.
Blake Belladonna is an independent, intelligent Badass Bookwormcat Faunus whose idealism and and passion for justice is well-hidden by her cynical comments and her tormented past. She is willing to work herself to death to make sure that her people aren't exploited. Her moral compass causes her to abandon the White Fang, the group she'd grown up under, when she sees that they've become needlessly antagonistic towards humans (the people that have abused Faunus since who knows when). She isn't powerful like Yang, but she's agile and stealthy with Gambol Shroud, an intricate (yet practical) and difficult-to-wield 4-in-1 weapon (a katana, a sheath that serves as another sword, a whip, and a gun). She singlehandedly defeated one of RWBY's most dangerous foes in a fight. She isn't afraid to insult those who deserve it, despite her withdrawn personality.
It's a shame Sun Wukong doesn't get more attention from the actual show itself. He's a gorgeous monkey faunus who is adorably smitten with Blake and effortlessly a smooth individual, who shows evident love of action but important concern over his friends. He's also an intense badass in a fight, at one point knocking a man flat on his ass with a punch from his tail...and then beating around baddies like rag dolls with a Bo staff, and unloading 40 shotgun blasts in five seconds from the shotgun-nunchucks his staff splits into. He's also good enough to not only get into the finals round among only seven other fighters in a worldwide tournament with hundreds of combants more experienced than him, he did it while the Big Bad was actively trying to plot and prevent him doing it. Yang and Pyrrha are there not without any lack of skill, but Cinder's machinations also made sure they got there. Sun unknowingly flipped off the Big Bad by showing how badass he can be....albeit offscreen.
No love for Ruby? She's easily one of the most adorable protagonist, is skilled with the scythe, and is all around a good person. What makes me admire her is her determination even after the devastating losses in volume 3.
Eugene, Matt Santoro's clone. He can make it snow with his warlock powers, he's a badass with his lightsaber, and is easily the funniest character. Need proof that he's the funniest character? In How to be Popular, Matt teaches him how to be popular (hence the title), and tells him to express his style. So, he dances to the song "Sexy and I Know It" by LMFAO, and he even twerks! That's comedy gold.
Korak from High Rollers. After being a figure shrouded in mystery thanks to some great storytelling and the two utterly opposing views of him (a slave owner and oppressor vs a champion and a hero), the former view turned out to be a misunderstanding and he turned out to just be... a genuinely Nice Guy, hailed as a hero, yet who is too ashamed of his past to tell of it, and of his real name to even use it - which is heartbreaking. The fact that instead of using his 'hero' status to be an ass and brush off Jiutou and her allegations, or even have her locked up for attacking him in an important fight, he let her go on her way and later sat down to have a rational conversation and address the issues raised with an uncommon and touching frankness and honesty does him credit. In addition, he has a humility about him (seen in his interaction with Jiutou in episode sixteen 'I did not want to disturb you with my presence...') which is utterly adorable, and a sense of humour (or at least a will to save face for Cam) as seen at the end of the same episode. And to top it all off, he is a seven foot tall red-and-gold humanoid dragon paladin, clad in golden armour and wielding a mystical crystalline blade.