Adjectives

(s)retiring, unassumingnot arrogant or presuming“unassuming to a fault, skeptical about the value of his work”, “a shy retiring girl”
(s)past, preceding, retiringof a person who has held and relinquished a position or office“a retiring member of the board”
(s)reticent, self-effacing, retiringreluctant to draw attention to yourself