The trailer for the Mortal Kombat 11 Kombat Pack is mostly focused on showing off Shang Tsung and his ability to shapeshift into a variety of palette-swap ninjas, which actually looks much cooler than I've just made it sound. The trailer also lists several other characters coming as part of the DLC—Sindel, Nightwolf, and comic book antihero Spawn—then mentions "two more guests will be revealed".
Fans have identified the music that plays behind this as being from The Terminator, and the blood-spatter, loading gun, and chainsaw sound seem like pretty obvious nods to Ash from the Evil Dead movies. Both these characters had been suggested by a datamine of the Switch version, a rumour Bruce Campbell seemed to debunk with this amazing tweet:
Consider this my finishing move against a certain internet rumor. pic.twitter.com/6vKPZvTfQuMay 6, 2019
However, Campbell is now retweeting the trailer and saying, "Boy, looks like a swell game - I’ll have to check it out!" Seems like maybe he was just messing with us all along.
That datamine also included the Joker, who could potentially be part of a second DLC pack.