Nil-Saint-Vincent-Saint-Martin (Walloon: Nî) is a Belgian village and district of the municipality of Walhain, Wallonia in the province of Walloon Brabant. The villages of Nil-Saint-Vincent and Nil-Saint-Martin were merged in 1812. 'Nil' is the name of a small river, along whose valley the various areas of settlement (Nil-Pierreux, Nil-Saint-Vincent, Nil-Saint-Martin) lie.