Dr. Strange is the protagonist in the movie of the same name. He was revealed by past employees post-cancellation. He was going to be playable in Disney Infinity 3.0.
Not much is known about Dr. Strange besides his figure design and rough estimation of release (around the same time as his film). He also was going to be playable in the Marvel Battlegrounds playset.
Dr. Strange was going to arrive in Disney Infinity 3.0 via an update, but is now scrapped because production on Disney Infinity ended.