There is a new THX trailer in 2015 named "Eclipse" which when we see the space-like background, we see the eye-looking eclipse zooming in, and we see the dark THX logo with the slogan "See You on the Other Side". The more scarier version of the deep note is playing.
THX is a sound system created by Lucasfilms shown in many movies made from 1995 until 2005. The logo has been parodied on shows like Family Guy and The Simpsons.
Medium bordering on high. - The Loud, Booming Music (Known as the Deep Note)can scare the people with THX-phobia. The scare factor is low for non-thx phobics.
Medium to high for the Eclipse version. The dark atmosphere, and the more scarier deep note may scare some first time viewers and runs away from the theatre. The Eclipse trailer is more scarier than the other trailers.
WATCH IF YOU DARE!!!Edit
WARNING! These logos may give you Nightmares!!!
Scariest THX logo yet!