Dr. Kimberly Shaw from Melrose Place.

The top pyscho on TV as far as I'm Concerned, that I'm surprised failed to make the list is Dr. Charles Henry Moffett from the 80's tv show Airwolf.
Though Moffett only appeared as himself in the pilot episode and once again in season two as a ghost in Airwolf's computer his behavior isn't anything short of pyscho.

What makes him a canidate?
To begin with he stole the ultra high tech attack helicopter, Airwolf. Used the weapons on the aircraft to destroy the test site and his coworkers.
He also stuck a revolver in the mid-air refueling port in Airwolf, cocked the hammer and fired only to get an empty 'click'
Upon this, a Lybian soldier said: "You are insane Doctor"
To which he replied "No I'm actually bored"
Then in order to 'question' a dancer at a bar on behalf of the Lybians he uses Airwolf to sink an American Naval Destroyer.
But what makes him the top pyscho is when he staked another dancer who was the love of the hero Stringfellow Hawke, to a sand dune in front of the Mediterrian Ocean. and told her "We can be there in ten minutes, but no that would be cruel the Mediterrian is very salty."
In season two, he was a ghost that controlled Airwolf's onboard computers.
So even in death he was insane.

no Jim Profit? That guy was insane! Instead of killing people himself like Dexter, he makes others do it for him!:D

I have to agree about Nancy Grace - i realize that's what they pay her for, but I wonder how she feels about the woman she drove to suicide?

Nancy Grace, John (America's Most Wanted) Walsh, O'Reilly, Sean Hannity, and Glen Beck, are the biggest psychos on TV.

I can't believe you left out two of the GREATEST TV psychos of all time! Bob from "Twin Peaks," and the never-seen television personality who had one of the best theme songs of all time as well: Psycho Dad from "Married With Children."

Dru is pretty awesome, though pretty much all vampires psychos, probably coulda squeezed Angelus on in place of Monk, who is almost painfully benign in his "craziness."

And ditto on Oz. The way Schillinger (the neo-nazi) systematically killed all of Beecher's family including mailing him his 8 (?) year old daughters hand, or how keller broke both beecher's arms and legs, and then AFTER that managed to seduce him into an absurdly twisted relationship. It took me years to be able to watch Chris Meloni on SVU and not see a psychokiller/rapist (Which makes SVU very confusing). Oh and which guy was it who chained the priest and built a brick wall in front of him, leaving him to starve to death?

Oz was psycho-city, seriously.

Come on, you have to have Sylar!! He's the first person I thought of when I read the article title. I also put forth River Tam, T-Bag, and possibly House.

There was no need for the others. You could've easily ended the topic with ten entries about how amazing Dexter Morgan is.

Though, no Sylar is kind of a shame. =/

T-Bag from Prison Break, Lincoln Meyer from Boston Legal, Cartman from South Park, The Master from Doctor Who, Stewie from Family Guy, Catbert from Dilbert are just a few that popped in my head...