Marcílio Moraes was born in the city of Petropolis, Rio de Janeiro (RJ). He is a short story writer, novelist, playwright, and screenwriter. He initially studied Language and Literature at the former National School of Philosophy (FNFi). He has worked as a teacher, translator, journalist, theatre critic, publicist, proofreader, dictionary compiler, and technical advisor to the National Art Foundation (Funarte).
His first short story was published in 1969 in the magazine Cadernos Brasileiros. In the 1970s, he wrote short stories and, under a pseudonym, penned adventure books that were sold at newsstands.
In 1974, Marcílio began his career as a playwright. Plays like Mumu: A Vaca Metafísica (Mumu: The Metaphysical Cow) Sonata sem dó (Sonata Without Mercy), Correntes (Chains), and "Aracelli" are among his most famous works in the theater. He received awards from the former National Theatre Service and the "Author Revelation" award from the São Paulo Association of Art Critics (APCA).
In the 1980s, Marcílio Moraes transitioned to television, beginning his career at TV Globo with the miniseries A Juíza (The Judge) by Armando Costa and Ferreira Gullar. He continued to contribute to TV Globo, with special mention to his work on "Roque Santeiro" alongside Dias Gomes. Throughout his television career, he has written for soap operas such as Roda de Fogo (Wheel of Fire), "Mandala," Mico Preto (Black Howler Monkey)," “Dream of Mine," and the remake of Irmãos Coragem (Coragem Brothers). Furthermore, his talent extended to miniseries, including Laércio é Nosso Rei (Laércio is our King), “The Brides of Copacabana," "Dona Flor and Her Two Husbands," and "Chiquinha Gonzaga," as well as noteworthy specials such as "The Big Family," O Dia Mais Quente do Ano (The hottest day of the year), and Aventuras de um Barnabé (The Adventures of a Barnabas).
Marcílio Moraes left TV Globo at the end of 2002, and his debut novel, O Crime da Gávea (The Crime of Gávea), was published in 2003 by 7 Letras. In addition to his writing career, he was also elected president of the Screenwriters’ Association, a position he held until 2010.
Hired by Record TV in 2005, he wrote the soap operas "These Women," "Opposite Lives," (winner of several APCA awards and the Troféu Imprensa award) and "River of Intrigues," as well as the series "The Law and the Crime," in 2009, “Crossing the Line," in 2012, and "Obscure Power," in 2014.
Marcílio Moraes wrote, produced, and signed the film O Crime da Gávea (The Crime of Gávea), released in 2017. In 2018, the publishing house 7 Letras released his second novel, Entre as Estrelas: Aquiles (Among the Stars: Achilles). He is currently the author of De Peito Aberto (Comédias, Dramas e Tragédias) — O Teatro de Marcílio Moraes (Open-Hearted (Comedies, Dramas, and Tragedies): Marcílio Moraes' Theatre).