Marco António Chagas Martins (born November 19, 1956 in Pontével, near Cartaxo) is a former professional racing cyclist from Portugal. He is one of the best Portuguese cyclists, having won 4 times the Volta a Portugal, in 1982, 1983, 1985 and 1986, making him the second most successful rider in the competition, behind David Blanco, a 5 times winner.

Marco Chagas is now the cycling commentator on RTP.