apologizer

Agent noun of apologize: one who apologizes.

(British, English, Oxford, US, intransitive, often) To make an apology or excuse; to acknowledge some fault or offense, with expression of regret for it, by way of amends
(British, English, Oxford, US, intransitive) To express regret that a certain event has occurred.
(British, English, Oxford, US, dated, intransitive) To make an apologia or defense; to act as apologist.