May you find your Tower, Roland, and breach it... and may you climb to the top!
Who: Father Donald Callahan
Source: The Dark Tower VII: The Dark Tower
Note: Character, quickly becoming overwhelmed by vampires and "low men" in an attempt to buy time for Jake to flee deeper into the hidden enemy headquarters in the Dixie Pig, was calling out one last message across time to his separated allies; his final message, above, is to Roland Deschain. He then commits suicide rather than be killed and possibly turned by the vampires overwhelming him.