The Mortal Kombat franchise isn't afraid to open up its gates to characters far outside of its normal roster when it comes to DLC, and Mortal Kombat 11 is no difference. There's been some unique faces joining the game in this installment, with the most recent being Spawn. In an interview with IGN, Mortal Kombat co-creator Ed Boon talks about how that came to be.
We have always wanted to have Spawn in one of our Mortal Kombat games. I’ve heard a number of times that Todd McFarland expressed interest in seeing Spawn in Mortal Kombat. As far as the fans are concerned Spawn is probably one of the most requested characters ever to be in the franchise. He really is a perfect fit.