narcissist n.

1905, from German Narzissismus, coined 1899 (in "Die sexuellen Perversitäten"), by German psychiatrist Paul Näcke (1851-1913), on a comparison suggested 1898 by Havelock Ellis, from Greek Narkissos, name of a beautiful youth in mythology (Ovid, "Metamorphoses," iii.370) who fell in love with his own reflection in a spring and was turned to the flower narcissus (q.v.). Narcissus himself as a figure of self-love is attested by 1767. Coleridge used the word in a letter from 1822.

But already Krishna, enamoured of himself, had resolved to experience lust for his own self; he manifested his own Nature in the cow-herd girls and enjoyed them. [Karapatri, "Lingopasana-rahasya," Siddhanta, II, 1941-2]

Sometimes erroneously as narcism.

word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.