Antonyms of egotist :
altruist, humanitarian, philanthropist.
Examples of usage:
For the egotist is he who makes claims upon others, and the Individualist will not desire to do that. "The Soul of Man", Oscar Wilde.
And he admired himself while I dressed in hot haste: a fine young fellow; not at all the natural egotist, but cast for death by the doctors, and keenly incredulous in his bag of skin. "Dead Men Tell No Tales", E. W. Hornung.
The most offensive egotist is he that fears to say " I" and " me." "A Cynic Looks at Life Little Blue Book #1099", Ambrose Bierce.