Marcus Gratidius (d. 102 BC) was a Roman statesman and orator from Arpinum during the late second century BC. He is best known as a result of his connections with Cicero and Marius.
Gratidius' sister, Gratidia, married Marcus Tullius Cicero, grandfather of the celebrated orator. His wife was Maria, sister of Gaius Marius, and they had at least one son, Marcus, who was adopted into the Marian gens, probably by his uncle, Marcus, after the elder Gratidius' death, and became known as Marcus Marius Gratidianus. A Marcus Gratidius who was legate to Quintus Tullius Cicero in Asia, from 61 to 59 BC, may have been his grandson.
Marcus Gratidius first appears in history as the proposer of a lex tabellaria at Arpinum. The law was opposed by Gratidius' brother-in-law, Marcus Tullius Cicero, who brought the matter to the consul Marcus Aemilius Scaurus. Scaurus agreed with Cicero, whose courage and opinions he praised, so it seems that the law was not passed.
Gratidius was a clever man and naturally talented in oratory; he was learned in Greek literature; and among his friends was Marcus Antonius, the orator and grandfather of Marcus Antonius the triumvir. Probably early in 102 BC, he gave testimony against Gaius Flavius Fimbria, who had probably been accused of repetundae, or extortion, in the administration of his province the previous year.
Later that year, Gratidius accompanied his friend, the praetor Marcus Antonius, who had been assigned the province of Cilicia, and given proconsular authority in order to fight the pirates. Gratidius served as prefect under Antonius, and was killed in the course of the campaign.