Fabius Aconius (or Aco) Catullinus signo Philomathius (floruit 338-349) was an aristocrat and a politician of the Late Roman Empire.
Philomathius was the son of Aconius Catullinus, Proconsul of Africa in 317-318, and had a daughter, Aconia Fabia Paulina, who married the influential pagan senator Vettius Agorius Praetextatus.
Philomatius held the offices of Consul suffectus, Praeses of Gallaecia, vicarius of Africa (338-339), Praetorian Prefect of Italy (attested on 24 June 341, out of office before 6 July 342), Praefectus urbi of Rome in 342-344 and finally Consul in 349.
A pagan, he obtained an exemption for the temples in Rome from the ban over the celebration of pagan sacrifices (Codex Theodosianus, xvi.10.3); a dedication to Jupiter Optimus Maximus by Philomathius has been preserved (CIL II, 2635).