Ned Flanders isn’t primarily because Homer Simpson is. However, if The Flanders became a spin-off (with The Simpsons only having an occasional visiting guest role) then Ned Flanders would be.
Chris from Family Guy, excluding any brother-type stuff he does to Meg (and let’s face it, everybody is mean to Meg these days).
Manny from Black Books, the unfortunate bout with Dave’s Syndrome notwithstanding. 
Kari from Digimon. She had to be little miss perfect all the time. Yes, it’s a children’s cartoon and an anime, but she stands out even amongst them.
Betty is a crazy crazy stalker. And crazy. Google ‘“Betty Cooper” insane’ for supporting evidence.
I came in to say Barney Miller, but Don’t Ask beat me to it.
So I’ll go with another Cap’n: Frank Furillo.
mmm
James Patterson’s Alex Cross - to the degree that I felt it just wasn’t a realistic portrayal of a human being. The guy just always seems to be so empathic, kind, understanding, and good, it was almost sanctimonious.
Now, to be fair, I only read a couple of these novels before I tired of the character, so it’s quite possible he was dick elsewhere in the interminable series.
There’s an episode where the most popular girl in school gives him a makeover and starts dating him. His response is to use his new popularity to bang other girls. (He’s also mean to Meg in that episode, but everyone is all the time).
Mary Richards.
Erin from The Office.
She was kinda dickish to Betty Ford.
More than Phil Esterhaus? I still miss him.
And Mr. Hooper.
Erin had quite the attitude about Holly, Michael’s ex fresh in from New Hampshire.
Lance White got there first, on THE ROCKFORD FILES. 
Justine from the Marquis de Sade’s books.
She deserves it - she didn’t even bring them decent candy!
You don’t remember the scene when she was a child and was on her neighbor’s roof, unplugging his aerial during the football game? He richly deserved it, but she was definitely being a brat - the childish equivalent of a dick.
Mr. Miyagi.
Yvonne from Casablanca.
Because the US is one of the least pro-gay western democracies in the world? And that show was aired over 15 years ago when it was even less down with the gays. What did you expect for what was essentially a mainstream soap opera?
Quite a few of Tolkien’s characters were pretty decent types, Galadriel and Tom Bombadil spring to mind.
Gomer Pyle, USMC
Uncle Jessie from Dukes of Hazzard
Batman, Commissioner Gordon, Chief O’Hara, Robin, Alfred
Aunt Bee