The shorter the original run the better. Does anything beat the 6 episodes of Police Squad?

The Dana Carvey Show (1996) 7 episodes

Police Squad! is tough to beat with The Naked Gun franchise.

Freaks and Geeks (18 episodes)
Launched careers of Seth Rogen, James Franco, Jason Segel, Linda Cardellini, Busy Philipps, etc.
Became the template for authentic teen dramedy.
Hugely influential in comedy tone and casting pipelines.

Firefly (14 episodes)
Spawned a feature film (Serenity), comics, novels, and a diehard fandom. An animated series (https://sitcomsonline.com/boards/showthread.php?t=508235) is in development.
Helped cement Joss Whedon’s cult status.
Its “space western” tone keeps getting imitated.

I will go with Police Squad! It was a very funny show with many sight gags that was canceled for an inane reason. An ABC network executive felt that the show "demanded too much attention of the viewer" due to the abundance of sight gags in each episode.

Square Pegs had 20 episodes.

The Who’s The Boss spinoff, Living Dolls. 12 episodes. While the show itself may not be memorable, it is remembered as the first acting job for Halle Berry, who went on to do some things you may have heard of.

The Jetsons (24 episodes)