Bluto appears to have developed an unhealthy obsession with Popeye and Olive Oyl. I think he probably counts as a stalker.
Gargamel from the Smurfs has some kind of psychotic disorder, being as how he constantly sees smurfs everywhere. I know they don’t exist; you know they don’t exist. Try telling Gargamel.
Opus from Bloom County is a hapless eccentric who could probably use about ten years of therapy to get him over his abandonment issues, but it may be safer to leave him be.
The President in Doonesbury is invisible. Therefore the entire populace is hallucinating.
Cartman has problems with anger, malice, and perhaps tourette’s syndrome.
Steve Dallas from Bloom County is a narcissist and a sexual compulsive. On having his brain flipped by the aliens, he is clearly suffering from the conviction that he is Alan Alda. Delusional, at best.
Charlie Brown is neurotic to the point of insanity. Lucy has control issues, and may be obsessed with Schroeder. Linus is suffering from religious mania over the Great Pumpkin. Pig-pen, however, does not suffer from low self-esteem. He just stinks.
Marvin the Martian is xenophobic.
Inspector Clouseau from the Pink Panther cartoons is an obsessive.
Tank Girl has problems with authority.
Spy vs Spy are both obsessives. And given the length of time the strip’s been running, it’s probably time they were called out of the field. Chances are their countries have been friends for decades by now.
Bam-Bam is hyperactive. And destructive.
Judge Dredd is a 100% Grade-A loon on a bike.