Seymour Skinner, born as Armin Tamzarian, is the principal of Springfield Elementary School. He is a Vietnam War Veteran and instead afraid to mention it. His arch rival is Bart Simpson who has played humorous pranks on him - and half the time Bart ends up suspended/expelled because of his actions. He has fooled around with Edna Krabappel and almost married her. His mother is called Agnes who plays a demanding authoritative near-suffocating mother on his side. Nonetheless, Skinner is very obedient towards her, even at some points having to choose between her woman Edna and her mother, and choosing his mom over.
Skinner also fears his superior, Superintendent Chalmers. He is often yelled at, hence Chalmers' catchphrase being "SKINNER!!" as he often disapproves Skinner's motives and decisions throughout the school. In comedic fashion, that has been spread out onto things not concerning school.
When it comes to Seymour's love life, look no further than Edna Krabappel. Both have dated each other several times, and the first time it was publicly known, it caused an uproar amongst the town. Chalmers offered an ultimatum for Skinner; either to end the relationship or getting fired. Skinner chose Edna and both got subsequently fired before they won back their jobs by pleading to the Springfield town mass. Later on, he and Edna keep on dating and at one point they get engaged. The marriage never went through, but they still hold eyes towards each other. Before the whole ordeal, in the second season, Skinner dated Patty Bouvier, who later on broke up with Skinner by fear of not letting her other sister Selma alone.
He is generally known as being intelligent and knowledgeable; he is a member of Mensa and has spent years in the army, performing duties in the Vietnam War. Despite that, he remains clueless and somewhat indifferent when it comes to bullies threatening others or showing hints at it.
The Principal and the Pauper is the episode which portrays most of the Armin Tamzarian story. The story being that during the army, Sergeant Skinner and Armin became close friends and at one point, Sgt. Skinner appeared dead. Armin blamed himself for it, and wanted to deliver the news himself to Agnes, and when he saw her, he felt so bad for the situation ongoing and posed himself as being Skinner, whilst Agnes purposely mistook the man for her son, and everything went on from there.
At another point, Skinner gets fired because of Bart's shenanigans. Ned Flanders takes over as the principal while Skinner goes back to the army. Bart realizes he loved having Skinner as his arch enemy and thus creates a plan to lure him back. Their plan failed but Chalmers ended up firing Ned - and hiring back Skinner - when he heard him pray the Lord over the intercom.
Seymour Skinner: " For privacy's sake, let's call her Lisa S. Wait that's to obvious. How about L. Simpson?"