Publius Acilius Attianus (1st – 2nd century AD) was a powerful Roman official who played a significant though obscure role in the transfer of the imperial power from Trajan to Hadrian. He was born in Italica, Hispania Baetica, which was also the birthplace of Publius Aelius Hadrianus Afer, the emperor Hadrian’s father. When Afer died about 86, Attianus and the future Emperor Trajan (another native of Italica) became the ten-year-old Hadrian’s guardians. Otherwise nothing is known of Attianus’s early career, but towards the end of Trajan’s reign he was joint Praetorian Prefect with Servius Sulpicius Similis for colleague. While Similis remained at Rome, Attianus accompanied the Emperor on campaign in the East. Attianus was present at Trajan’s deathbed at Selinus in Cilicia in August 117 and helped the Empress Plotina secure the succession of Hadrian, either by pleading his case or, as was also alleged, helping to forge Trajan’s will. Along with Plotina and Matidia, Attianus accompanied Trajan’s body to Seleucia and his ashes to Rome. He counselled Hadrian on his accession against various possible opponents, and according to Hadrian’s lost autobiography it was Attianus who was responsible for the murder of the ‘four consulars’ whose deaths were an early stain on his reign. Hadrian resented Attianus’s power and in 119 induced him to request to be relieved of the post of Praetorian Prefect. He was given senatorial rank and the ornamenta consularia on his retirement; nothing more is heard of him.