Unitarian theologian, writer, and lecturer. Younger brother of Harriet Martineau. Ordained, 1828. Had ministries in Dublin and Liverpool. Professor of mental and moral philosophy and political economy, Manchester New College, 1840; professor of mental, moral, and religious philosophy, 1857 (by which time the college had moved to University Hall, Gordon Square, London). Minister of Little Portland Street Chapel, London, 1859. Principal of Manchester New College, 1869. Gave up preaching owing to ill health in 1872.