Dr. Kleiner

Dr. Kleiner is an Old Man originally coming from Half-Life who appeared in the video "SwagQuest".

Appearence
When Luigi is not allowed to go to Mario's party because he doesn't have enough swag, he seeks lessons from Bowser on how to obtain swag. After a few minutes, Bowser tells Luigi to change his clothes, to add swag. After four clothes changes, Luigi and Bowser settle on a gangster costume. Then, Dr. Kleiner runs up to Luigi and slashes his clothes off, causing Bowser to force Luigi to fight the Old Man, stating that he "ruined Luigi's swag." Luigi is afraid at first, but gains the courage to insult the Old Man, calling him creepy. The Old Man gets angry and Luigi starts rapping. The Old Man reminds him that this is a fight, and a short battle ensues. The Old Man strikes Luigi with a multicolored ball, who counterattacks with a "Big Gay Dance." The Old Man then throws a fireball at Luigi, who ducks as it ricochetes off a tree, blasting the former into the air and crash into a boat, which sinks (then Luigi does a short victory dance).

Trivia

 * Dr. Kleiner looks similar to a nerd who appeared in the last skit of the blooper "Ssenmodnar 6.64 (100k special Qna Edition)". Maybe are they the same Old Man.

Note
On this Wiki, we also call him "Old Man", but, in this case, he mustn't be confused with the Old Man Hobo (who doesn't appears in the video "SwagQuest" (except in the top right corner of the screen, of course, because he is this corner in every video of SuperMarioGlitchy4 now)).