One animator animated an entire feature film all by herself:

Nina Paley’s Sita Sings the Blues … tells two parallel stories: the ancient Hindu epic the Ramayana and the breakup of Paley’s 21st-century marriage. It does so through four distinct styles of animation, a “greek chorus” of Indonesian shadow puppets and wildly imaginative musical interludes that use authentic 1920s blues recordings to link narratives 3,000 years apart.

Solo Animator's 'Sita Sings the Blues' Makes Tribeca Film Fest