Cable Guy

The Cable Guy is the titular main antagonist of the 1996 black comedy film of the same name.

He's a mentally unstable cable installer who gets obsessed with one of his customers, Steven Kovacs. After his numerous friendship advances get turned down by him, he ends up becoming a fully-fledged stalker, hellbent on destroying his life.

He suffered mainly from loneliness because of his childhood neglect which is why he was too over keen to make friends and making bad decisions (such as stalking) in the process. When Steven gently turned him down, Chip's true colors of being vengeful and insane were revealed as he went to great lengths just to ruin the latter's life for seemingly petty vendetta. His childhood neglect also eventually caused him to flock to television and movies to replace the company and affection he never got, causing him to warp and mold his personality around the media he consumed, something that, in turn, explains his erratic behavior. His obsession with making friends also seems to stem from his childhood as he seemed to have yearned for a younger brother as a kid, with his mother not listening to his demands, something that might explain his attachment issues later in life.