His most famous written works were the exploits of Feluda, a Bengali detective. Feluda, whose real name was Pradosh Chander Mitter, was often accompanied in his exploits by his assistant Topshe (his cousin), and Lalmohan Ganguly, or Lalmohan Babu (alias Jatayu), a bumbling writer of crime fiction.
Satyajit Ray wrote thirty-five Feluda stories, most of which were extremely popular among Bengali children. Humour was an important aspect of the Feluda adventures. Some of the more famous ones include "Sonar Kella" (The Golden Fortress) partly set in the desert fortress of Jaisalmer in Rajasthan, and "Joi Baba Felunath" which was set in Varanasi. These adventures were made into movies in Bengali starring actor Soumitra Chatterjee(who had previously appeared in several of Ray's films) as Feluda. A more recent film is Bombaiyer Bombete (released Dec 2003), which stars a new set of actors; this film was made by Ray's son Sandip Ray (also a film-maker).
During the late 1980s, the detective Feluda also appeared on Indian television with actor Shashi Kapoor starring as Feluda.