Marcus Annius Libo was a Roman Senator active in the early second century AD.
He was the son of Marcus Annius Verus, consul III in 126, and Rupilia Faustina.
His elder sister was the Empress Faustina the Elder (mother of the Empress Faustina the Younger) and his younger sister (whose name is missing, but surmised to be Annia) was the wife of Gaius Ummidius Quadratus Sertorius Severus, suffect consul in 118.
During the reign of his brother-in-law, Antoninus Pius, he was one of seven witnesses to a Senatus consultum issued to the city of Cyzicus in 138, which sought approval for establishing a corpus juvenum for the education of young men.
[5] Libo married a noblewoman whose name has been surmised as Fundania, daughter of Lucius Fundanius Lamia Aelianus, consul in 116, and wife Rupilia Annia.