A funeral march, as the name would indicate, is a slow march often played during funerals and other sombre moments. Funeral marches are usually in minor keys; the most famous funeral march was probably the one written by Frederic Chopin, originally the 3rd movement of his Piano Sonata No. 2, in b-minor, op. 35 .
Other examples in classical music include:
Usually funeral marches are in a slow "simple duple" metre, imitating the pace when walking behind a coffin to a graveyard. Nonetheless, the 2nd movement of Brahms' Deutsches Requiem has been called a "Funeral March in triple metre".