Will-o'-the-Wisp (Portuguese: Fogo-Fátuo) is a 2022 Portuguese musical romantic comedy film, directed by João Pedro Rodrigues. The film stars Mauro Costa as Alfredo, the crown prince of Portugal whose ion for the environment leads him to become a fireman, where he falls in love with colleague Afonso (André Cabral).

The film contains a number of choreographed dance numbers set in the firehouse, and includes references such as Alfredo directly quoting parts of Greta Thunberg's 2019 speech to the United Nations when trying to defend his choice to his disapproving family.

The film's cast also includes Joel Branco, Oceano Cruz, Margarida Vila-Nova, Miguel Loureiro, Dinis Vila-Nova, Luisa Castelo Branco, Vasco Redondo, Teresa Madruga, Ana Bustorff, João Mota, Paulo Bragança, Anabela Moreira, Raquel Rocha Vieira, Cláudia Jardim, Joana Barrios and João Villas-Boas.