I agree with you on not being a fan of guest characters in MK games, there hasn't been a single one I like yet. However, if I had to see some in MK 11 I'd want to see:

1. Lara Croft from Tomb Raider(Camilla Luddington): By far my first choice, I'd want to see the 2013, Rise, Shadow era of Lara, not the lame ass one from the 1990's and 2000's. Imagine the fatalities and fatal blows with the climbing hooks and bow/arrow.

2. Robert McCall from The Equalizer 1 & 2(Denzel Washington): Coolest non-superhero hero in a modern film. Dude can kill anyone with any object, including a book.

3. Riley North from Peppermint(Jennifer Garner): A mother/wife with nothing to lose. Brass knuckles and a blade for a fatal blow please.

4. John Wick(Keanu Reeves): also a cool Equalizer type character that I feel would fit in well in the MK universe. Give us a fatality with a pencil.

5. Selene from Underworld franchise(Kate Beckinsale): Nitara would be better, but also another cool action movie heroine.

Lastly, I love the Shenmue franchise more than anything in video games, so seeing Ryo Hazuki or Lan Di would be cool for me, but I don't feel they would fit into the MK universe well like the others listed above, though I'd still take them over any guest characters we've gotten so far from MK 9, X and 11.

The only guest character I would wanna see is 2B

#2BforMK

No guest characters.

Assassin's Creed main protagonist, Altaïr Ibn-La'Ahad.

If Guest Characters Stay a thing NRS needs to Make sure That The Other Companies Know that NRS shouldnt Have to EVER shut Online Game Functions Down Because of 1 Character. Otherwise Guest Characters Shouldnt Happen.

Illidan Stormrage

The Lich King

Mortal Kombat VS War Craft

I Also Think

The Mask Would Be A Very Nice Addition.

https://youtu.be/T1TrFjLKryc

Rick and Morty!!