Picking one is just not fair! So I'm making a short list of current favorites too.
Books:
Alanna of Trebond from Tamora Pierce's Lioness quartet - A girl who wants to become a Knight - of course only guys are knights.
Harry Dresden from Jim Butcher's Dresden Files Series - A Wizard P.I. He gets into all kinds of trouble. And nothing quite says class like showing up to a vampire's costume party as a VERY tacky Dracula.
I'm also starting to like Rachel Morgan from Kim Harrison's The Hollows series - A witch bounty hunter who lives with her partners - a Bi Living Vampire, and a very straight Male Pixie and his wife and 54 kids (Even if I started to reconsider my favorite name after I found her
)
Comics:
Ranma/Ranko: Martial artist who fell into the Cursed Spring of Drowned Girl and becomes a girl every time he's splashed with cold water. He can only change back by getting hit with warm water. For someone who constantly complains about being half girl "he" spends an awful lot of time as Ranko intentionally.
Deadpool: Nothing quite like constantly breaking the 4th wall for extra giggles.
TV:
Dr. Spencer Reid: FBI Behavioral Analyst on Criminal Minds. Cute, nerd boy.
(Ok I like Derek Morgan and Penelope Garcia on this show too
)
Abby Sciuto: Happy Goth, Super-Lab technician on NCIS