Samson Agonistes is a dramatic poem by John Milton, published in 1671. It tells the latter part of the story of Samson, a Biblical character who was granted great strength by God in order to perform heroic feats and combat his enemies.
La Belle Dame Sans Merci (The Beautiful Lady Without Mercy), is a ballad by John Keats, published in 1820. It tells of a knight who meets a beautiful woman, 'a fairy's child' and becomes 'in thrall' to her. Two slightly different versions of the poem exist and both can be read here. Several Pre-Raphaelite painters also took up the subject, including John William Waterhouse and Arthur Hughes.