Daniel William Mayer (1909–1996) was a member of the French Section of the Workers' International (SFIO), a socialist party in France, president of the Ligue des droits de l'homme (LDH, Human Rights League) from 1958 to 1975. He founded the Comité d'Action Socialiste in 1941 and was a member of the Brutus Network, a Resistant Socialist group. Mayer also supported the Libération-sud resistance movement headed by Emmanuel d'Astier de la Vigerie.