Is there a single word that describes someone who hates themself? (Antonym of narcissist)

Solution 1:

You’re asking a lot for one word.

The only reason that narcissist works as a single word is because of its extended use as a metaphor derived from classical mythology. In particular, it’s a direct reference to the myth of Narcissus, the boy who loved himself too much and others too little.

Unless you can find a figure from literature or myth to serve as a foil for both those properties at once, you’re going to have a hard time satisfying your request. And I can’t think of any.

The closest word I can find for someone who beats themself up too much, or doesn't have enough self-love, is a flagellant. But even that word is improved by an explicit self reference, as in an autoflagellant.

These aren’t common words, and you may risk being misunderstood. They might even get the wrong connotation altogether, such as being a masochist or religious penitent.

Trying to describe someone who hates themself with a single word is going to be hard, although I see why you would like one for this particular instance. Being too much the altruist or having a messiah complex won’t fit the parallelism of your phrase.

Solution 2:

I don't exactly have a word for someone who hates themself, but...

"You don't know him. He's the antithesis of not a narcissist, he is a defeatist"

If we agree a narcissist has a high self-esteem, then surely a defeatist hasn't. Somebody with a defeatist attitude is self-deprecating and generally displays a lack confidence and self-belief in themself. Whenever something positive happens in their life, they fail to cling onto it, or appreciate their good fortune. A defeatist will first convince him or herself that there is no hope, no bright tomorrow.

defeatist: a person who expects or is excessively ready to accept failure.

Vocabulary.com says

Having a defeatist attitude means that you give up before you've even started, like the runner who is so convinced he's going to lose the race that he doesn't even bother to go to the starting line. A defeatist is the opposite of an optimist. A defeatist is convinced that he's going to fail, and he isn't surprised when he does fail. This is how a defeatist might propose to his girlfriend: "I'm sure you're going to say 'no,' so why don't you just go ahead and reject me now."

Solution 3:

I think you may be mistaken about the general status of self-hater in English usage. The problem with running Ngram requests for hyphenated words is that the Ngram search program doesn't know what to make of hyphens (which, after all, appear frequently in textual material as end-of-line breaks between syllables of individual hyphenless words), so the results that Ngram returns are not (in this case) for "self-hater" but for "self – hater"—whatever that means.

In any event, a Google Books search for "self-hater" yields dozens of matches in published works going back to as early as 1850. For example, from an 1850 transaltion of Alessandro Verri, Roman Nights; or The Tomb of the Scipios:

This ever-during instinct is proofs against the cavils and dogmas invented, it would seem, for the purpose of driving man to utter desperation, or to make him a self-hater ; deeming himself a poor compound, neglected by heaven, and designed to return to dust.

From Thomas Moor, Counsels and Thoughts for the Spiritual Life of Believers (1882):

It is right in all things to avoid being a self-worshipper, but it is no less right to avoid being in this sense a self-hater.

From Margaret Oliphant, The Wizard's Son: A Novel (1884):

"At school, at home, abroad, in all your relations? Self-lover! My object at least is better than yours."

I am no self-lover ; rather self-hater, self-despiser."

"It is the same thing. Self before all. I offer you something better, the good of your race."

From Gerald Morgan, "Stevenson's Three Rogues," in The Yale Literary Magazine (March 1899):

There Herrick confessed to his impotency; confessed that he was weak, cowardly and a self-hater, and proved to the captain that he was no more fitted for accomplishing anything when right was against him than when it had been with him.

From Christopher Strong, "'There's Thou-sands in It!'," in The Green Book Magazine (July 1916):

This fellow was a water-drinker, and he laid it over all the hooch-hoisters I ever heard, even as Barnum & Bailey's lays it over the man on the corner dry-goods box selling Ogalalla Compound. Booze thickens the tongue of the self-hater and coarsens the work; but water, applied to the right organism, such as this under view, makes liquid and unending the discourse and, in the immortal words of Tennyson, flows around us coots forever, until it makes us haunt the fern.

And from Cornelius Hanford, General Claxton: A Novel (1917):

Knowing how others hated her, she became a self-hater. She was subdued and pitiable, as one who had purposely forfeited all right to the sustaining consolation of personal pride.

Altogether, a Google Books search for self-hater yields 110 unique confirmable matches scattered across 33 pages of search results.

The absence of self-hater from big dictionaries indicates that the word (1) isn't all that popular, and (2) has a meaning so clearly and fully derived from self-hate or self-hatred as not to require coverage in a separate dictionary entry. Because it is possible to generate hundreds of valid words by attaching the prefix self- to various nouns, dictionaries tend to limit themselves to covering only the most prominent combinations.

Obviously you are under no obligation to use self-hater if you dislike it. But I think that it is almost certainly the most common term in written English for someone who hates him- or herself.