Randall Flagg has been featured in Dark Tower.
Randall Flagg . He has a variety of names , usually with the initial letters `` R. F. '' but with occasional exceptions , such as Walter o'Dim ( originally envisioned by King as a separate character ) in The Dark Tower series . Flagg was a primary antagonist in King 's epic series , The Dark Tower , who tries to keep protagonist Roland Deschain from reaching the Tower ( the linchpin of existence ) so he can claim it for himself and become a god . The Dark Tower expanded on Flagg 's background and motivation , linking his previous appearances . Aside from King 's novels , Flagg was featured in a television miniseries adaptation of The Stand ( played by Jamey Sheridan ) and the upcoming Dark Tower film adaptation ( played by Matthew McConaughey ) . He has also appeared in Marvel Comics ' adaptations of The Dark Tower and The Stand .