Gianfrancesco Sigfrido Benedetto Marinenghi de Guarnieri (August 6, 1934 – July 22, 2006) was an Italian–Brazilian actor, lyricist, poet and playwright.

[1] His parents, the maestro Edoardo Guarnieri and the Harpist Elsa Martineghi, decided to move to Brazil in 1936, finding a new home in Rio de Janeiro.

In the next year that theater joined up with The Arena Theater, founded and directed by José Renato[2] His first play was "They Don't Wear Black Tie", put on stage for the first time in 1958 in the Arena Theater[2] Directed by José Renato, the case had great talents that had begun to attract attention, like Guarnieri himself, Leila Abramo, Miriam Melhler, Flavio Migliaccio, Eugênio Kusnet, Francisco de Assis, Henrique César, Celeste Lima, Riva Nimtz, and Milton Gonçalves; It was set to end the collective project, since they were having financial problems, but it had immense success.

The play, author and cast were given awards by the governor of São Paulo State, Janio Quadros, and the arena was saved from its financial troubles.

In the same year Guarnieri also participated of two other Flávio Rangel plays: Almas Mortas (Dead Souls) of Gogol, and the first showing of A Escada (The ladder) by Jorge Andrade.