The Marsh Wren, Cistothorus palustris, is a small songbird of the Wren family.
Adults have brown upperparts with a light brown belly and flanks and a white throat and breast. The back is black with white stripes. They have a dark cap with a white line over the eyes and a short thin bill.
Their breeding habitat is marshes with tall vegetation such as cattails across North America. The nest is an oval lump attached to marsh vegetation, entered from the side. The male builds many unused nests in his territory; he may puncture the eggs of other birds nesting nearby.