C. Atilius M. f. M. n. Regulus Serranus (fl. 250 BC) was a Roman Republican consul who twice held the consulship in the middle of the 3rd century BC. His elder brother, father, and grandfather were all consuls.

Regulus was consul for the first time in 257 BC, with the patrician Gnaeus Cornelius Blasio, and prosecuted the First Punic War against the Carthaginians. He defeated the Carthaginian fleet off the Liparaean islands, though not without considerable loss. He then obtained possession of the islands of Lipara and Melite, which he laid waste with fire and sword. On his return to Rome, he received the honour of a naval triumph (Polyb. i. 25 ; Zonar. viii. 12 ; Oros. iv. 8 ; Fasti Capitol.).

Re­gulus was consul a second time in 250 BC, with his patrician colleague being Lucius Manlius Vulso. In this year the Romans gained a brilliant victory at Panormus, under the proconsul Metellus. Thinking that the time had now come to bring the war to a conclusion, they sent both the consuls to Sicily with an army of four legions and two hundred ships. Regulus and his colleague undertook the siege of Lilybaeum, the most important possession of the Carthaginians in Sicily ; but they were foiled in their attempts to carry the place by storm, and after losing a great number of men, were obliged to turn the siege into a blockade. (Polyb. i. 39, 41—48 ; Zonar. viii. 15 ; Oros. iv. 10 ; Diod. Fragm. xxiv.)

According to William Smith, this Regulus is the first Atilius who bears the surname Serranus, which afterwards became the name of a distinct family in the gens. The praetor Caius Atilius Serranus, praetor in 218 BC and a failed candidate for the consulship in 216 BC, was his son and ancestor of all subsequent praetors and consuls from this family. One of his descendants Sextus Atilius Serranus became consul in 136 BC with Lucius Furius Philus (wrongly called Publius by Smith).