MMO versions are tough to include on these lists because their balance and resource management is approached in a much different way than single player games, but I do want to give a shoutout to FFXIV's red mage for having a unique function in endgame content when in most versions of this job you have to abandon it mid-game.

Of course in an MMO all jobs are useful endgame, but in FFXIV red mage is uniquely useful when progging end game content for its ability to instantly raise over and over. The healer jobs (plus summoner) in this game can only insta-raise once, then there's a very very long cast time if they need to do it again over the next 60 seconds. Red mage never needs more than 2 seconds to raise. You can be the only one left alive in the party and still be able to salvage the situation. You might have a full MP bar and can res almost the whole party back, or just have enough in you to get the white mage up so they can use their limit break, or even just buy a couple more minutes to see more of the fight and learn something for a more successful second attempt.