1. Merlin -- Simultaneously the smartest and the stupidest character. He runs around getting into the same magical trouble in every episode. He has mad skillz but is exceedingly naive, and relies on his charm and good luck to save the day. Merlin is adorable in a very Finn-ish way. He often sports a hipster-style scarf.
2. Arthur -- Struts around being buff and delicious, but looks ridiclous in every costume he wears. He usually sports one-shoulder armor that makes him look like a cyborg; when dressed up in hooded chainmail, he resembles a walking phallus. The entire show is just a teaser while we wait for the scene where Arthur takes his shirt off.
3. Morgana -- The king's mysterious ward whose purpose is to look hot and wear anachronistic dresses. She variously resembles Kat Dennings, Keira Knightly as Lizzie Bennet, Scarlett Johansson, Dianna Argon with dark hair, or Anna Kendrick. Morgana and Arthur have weird romantic tension where they act either like siblings or like they're betrothed.
4. Gwen -- The girl next door. She is Morgana's lady-in-waiting but also has hobbies like flower arranging and sewing, and she has plenty of free time for hanging out with Merlin. She's kind of bland in a cutesy/earnest way, but she does kiss Merlin when he wakes up from being poisoned. Gwen's costumes are horrible.
5. Gaius -- Court physician who is right about everything, but everybody usually ignores him. He constantly forgives Merlin for being an idiot, so he was probably a hardcore partyer in youth. Gaius has long shiny hair that is always perfectly straight despite the circumstaces. He is possibly the lovechild of Albus Dumbledore and Carol Channing.
6. Uther -- The bald king and Arthur's father. He needs to be reminded who Merlin is in every episode. He is a harsh ruler and usually reluctant to consider alternatives to his point of view; he is also not very good at single parenting.
So far, my favorite moment in the series was when Arthur says that his father never apologizes for everything, and then went and told Merlin he was sorry. Big man! I think the weird thing about this show is that the level of bromance is really low (or I've just been corrupted by SPN and Narniafic). I feel like Merlin/Arthur would be the lamest ship ever!
But, five episodes in is not a lot, and I'll keep watching the hope that things get hotter and more interesting. And more shirtless. Right?