Speaker for the Dead
Marcos was Novinha's husband. He died a few weeks before Andrew Wiggin arrived at Lusitania, of a congenital disease which caused his glands to turn to fatty tissues. Among other things, this rendered him sterile, and it was revealed during Andrew's speaking of his death that none of Novinha's children were actually fathered by him, but rather by Libo; the two agreed to this form of cuckoldry before getting married. Because of this, Marcos frequently beat Novinha, but she didn't resist because she felt she deserved it.
He was known for his surly temper, and habit of beating his wife, traits which earned him the epithet of Cão, which means dog in Portuguese. However, this personality was mainly brought on by the tormenting he received from his peers at a young age.
Marcos does not have a single line of dialogue.