“Mystic”, to be fair, was what the OG system called them, but then AD&D was the first edition to use the term “monk”, and each subsequent edition has had some form of the class present in either the PHB or supplemental texts. Technically, 1st Edition D&D did not have Monk as a player class.
They’ve been around since AD&D, which is almost the very beginning, yes.
Good old Magic User class.
“Mystic”, to be fair, was what the OG system called them, but then AD&D was the first edition to use the term “monk”, and each subsequent edition has had some form of the class present in either the PHB or supplemental texts. Technically, 1st Edition D&D did not have Monk as a player class.