Marcelo de Campos Velho Birck (born August 13, 1965) is a Brazilian singer-songwriter, lyricist, arranger and guitarist, best known for his work with influential rock band Graforreia Xilarmônica.

In 1983, alongside his younger brother Alexandre Birck, future TNT guitarist Luís "Tchê" Gomes and future Os Cascavelletes bassist Frank Jorge, Marcelo formed the short-lived band Prisão de Ventre, which lasted only for two years.

[4][5] In 1987, he reunited with his brother and Jorge to form, alongside Carlo Pianta, the cult band Graforreia Xilarmônica.

[6] In 2000 Birck teamed up with Thomas Dreher and Felipe Faraco to form Os Atonais; their first (and so far only) studio album, Em Amplitude Moderada, came out the same year, amid overwhelmingly positive reviews.

[11] Birck has also collaborated with Jupiter Apple on his 1997 debut A Sétima Efervescência, arranging one of the musician's most well-known songs, "Eu e Minha Ex".