Gracie Films was a film and TV company founded by James L Brooks in 1986. They produced hits such as Broadcast News, Big, The Tracey Ullman Show, Say Anything, War of the Roses, and most notably The Simpsons.
The normal version consists of a movie theater with multiple silhouettes of patrons talking and whispering. A woman in the back shushes them at once by raising her index finger towards her mouth and saying "Shhh!" The theater lights dim and an offscreen projector emits a blue light, revealing the company name in white with both words on top of each other with GRACIE being halfway shifted to the left of FILMS as a 9-note electric piano piece by Jeffrey Townsend plays.
The original one was around since April 5th, 1987 and ended on December 31, 1999. An enhanced version of this was seen on The Simpsons Hit and Run, The Simpsons Movie, and all 2000 to present Simpsons episodes since Take My Life, Please.
There is a Treehouse of Horror variant (not in earlier Treehouse of Horror stories) where the ssh sound effect is replaced with a girl shrieking (which sound a bit like Toko Fukawa from Dangan Ronpa) (a version with Regis Philbin yelling "My eyes! My beautiful eyes!" instead of the girl screaming in the Simpsons episode Treehouse of Horror IX) followed by a horror-type pipe organ rendition of the original jingle.
Low to Medium for the regular variant. The music is so cheesy, it could be scary to some. As for the "Treehouse of Horror" variant, High. due to the scream and organ.