Appius Annius Trebonius Gallus was a Roman senator, who was active during the reign of Trajan. He was ordinary consul in 108, as the colleague of Marcus Atilius Bradua.Alison E. Cooley, The Cambridge Manual of Latin Epigraphy (Cambridge: University Press, 2012), p. 468
Trebonius Gallus was born into the plebeian gens Annia.Pomeroy, The murder of Regilla: a case of domestic violence in antiquity, p. 14 His father may have been Appius Annius Gallus, one of the suffect consuls of the year 67; according to Olli Salomies, there is a consensus that his mother was probably Trebonia, a daughter of Publius Trebonius, consul suffectus in 53.Olli Salomies, Adoptive and Polyonymous Nomenclature in the Roman Empire (Helsinki: Societas Scientiarum Fennica, 1992), pp. 106f Gallus was related to the senator Marcus Annius Verus; Verus was a brother-in-law of Hadrian, and the father of Faustina the Elder, wife of Antoninus Pius and aunt of Marcus Aurelius.
Gallus had a son named Appius Annius Trebonius Gallus, who was consul in 139.
References
Sources Sarah B. Pomeroy, The murder of Regilla: a case of domestic violence in antiquity, Harvard University Press, 2007