"The Forsaken Merman" is a rhymed lyric poem written in irregular metre by Matthew Arnold, begun whilst he was studying at Oxford on a scholarship in the early 1840s, and which appeared in the poet's first published collection, The Strayed Reveller, and Other Poems, in 1849.

[1] The basic premise recurs in Danish, Norwegian, German, and Slavonic folklore.

[1] The Merman, a King of the Sea, marries an earthly maiden, and lives with her happily, for many years, but at last she leaves him for a visit to her friends, promising, however, to return.

[2] The story is told by the old Sea King, in what the reviewer Charles J. Peterson called "a wild, irregular melody", to his children.

[2] Many critics initially found most of the poems in The Strayed Reveller to be obscure and aloof, but "The Forsaken Merman" was highly praised by fellow-poet Algernon Charles Swinburne for its lyric beauty.