Doctor Strange: 31 Easter Eggs & References You Must See
14. Dormammu
Dormammu is as old an adversary for Doctor Strange as Baron Mordo is and the idea of Strange (and other Sorceror Supremes before him) having to keep him out of the Earthly realm is a big part of the comics. There too he dwells in the Dark Dimension seeking a way to take over Earth.
In the comics too Strange and Dormammu are forced into a pact when Strange helps save the demon from the Mindless Ones and Dormammu is forced to agree not to ever attack Earth again.
It's a shame they didn't go with the massive half-balrog sort of design traditionally associated with the character in the comics (as this design in the film is a little... silly). But at least they retained his big stripy face from far earlier comics appearances...