was praetorian prefect under Tiberius and Caligula. His origin was obscure (Philo, Legat. ad Caium, 4); he was perhaps a freedman by birth (Tac. Ann. 6.38); and the steps by which he attracted the notice and favour of Tiberius are unknown. Macro first appears in history as the conductor of the arrest of Aelius Sejanus, his immediate predecessor in the command of the praetorians, A. D. 31, The seizure of this powerful favorite in the midst of the senate where he had many adherents, and of the guards whom he principally had organised (Tac. Ann. 4.2), seemed, at least before its execution, a task of no ordinary peril. The plan of the arrest was concerted at Capreae by Tiberius and Macro, and the latter was despatched to Rome, on the 19th of October, with instructions to the officials of the government and the guards, and with letters to some of the principal members of the senate. Macro reached the capital at midnight; and imparted his errand to P. Memmius Regulus, one of the consuls, and to Graecinus Laco, prefect of the city-police (vigiles). By daybreak the senate assembled in the temple of Apollo, adjoining the imperial palace. Macro, by the promise of a donation, and by showing his commission from Tiberius, had dismissed the praetorians to their camp, and supplied their place at the entrance and along the avenues of the temple by Laco and his vigiles. He had also lulled the suspicions which his sudden arrival at Rome had awakened in Sejanus by informing him, as if confidentially, that the senate was specially convened to confer on him the tribunitian dignity, which would have been equivalent to adopting him to the empire. Sejanus therefore took no steps for his own security, but, had he shown any disposition to resist, Macro had secret orders to release from prison Drusus, son of Germanicus and Agrippina [DRUSUS, No. 18], and proclaim him heir to the throne. Macro presented Tiberius' letters to the consul in the senate, but withdrew before they were opened, since his presence was required at the praetorian camp, where the soldiers, jealous of the preference shown to the vigiles, were in mutiny, and, in the confusion that followed the arrest of Sejanus, began to plunder and burn the suburbs. Macro, however, reduced them to discipline by a donation of more than thirty pounds sterling to each man, and they accepted him as their new prefect. For his services on this day the senate decreed Macro a large sun of money, a seat in the theatre on the senatorian benches, the right of wearing the praetexta, and the ornaments of a praetor. But he prudently declined these unusual honours, and contented himself with the more substantial favour of Tiberius. He was praetorian prefect for the remainder of that emperor's reign and during the earlier part of Caligula's. Macro, whom L. Arruntius described as a worse Sejanus (Tac. Ann. 6.48), was unrelenting in his persecution of the fallen favourite's adherents. He laid informations; he presided at the rack; and he lent himself to the most savage caprices of Tiberius during the last and worst period of his government. Mam. Aemilius Scaurus was accused by him of glancing at Tiberius in his tragedy of Atreus, and driven to destroy himself ; the veteran delator Fulcinius Trio denounced Macro and Tiberius with his dying breath; and L. Arruntius died by his own hands, to avoid being his victim. As praetorian prefect Macro had the charge of the state prisoners--among others of the Jewish prince Agrippa (J. AJ 18.6), [AGRIPPA HERODES, No. 1.] and of Caligula. Tiberius, A. D. 37, was visibly declining, and, in a new reign, Macro might be even more powerful than he had been under a veteran and wary despot. Of the Claudian house there remained only two near claimants for the throne, --Tiberius, the grandson, and Caligula, the grandnephew, of the reigning emperor. In Roman eyes the claim of the latter was preferable, since by his mother Agrippina he was a descendant of the Julian house. Tiberius was an infant, Caligula had attained manhood, but he was a prisoner, and therefore more under the influence of his keeper. To Caligula, therefore, Macro applied himself; he softened his captivity, he interceded for his life, and he connived at, or rather promoted, an intrigue between his wife Ennia [ENNIA] and his captive. Tiberius noticed but was not alarmed at Macro's homage to Caligula. " You quit," lie said, " the setting for the rising sun." It was rumoured, but it could not be known, that Macro shortened the fleeting moments of the dying emperor by stifling him with the bedding as he recovered unexpectedly from a swoon. Macro certainly induced the senate to accept Caligula as sole emperor, although Tiberius had in his will declared his grandson partner of the empire. During the better days of Caligula's government Macro retained his office and his influence. But his services were too great to be rewarded or forgiven. According to one account (Philo, Legat. ad Caium, 4), Macro presumed to remonstrate with the emperor for his extravagance, his indecorous levity, his addiction to sensual pleasures, and his neglect of business. A rebuke which Agrippa might have offered and Augustus received was thrown away on Caligula, and was unseasonable in Macro. Dread of the prefect's influence with the guards at first induced the emperor to dissemble; he even pretended to design the prefecture of Egypt, a place of the highest trust (Tac. Ann. 2.59, Hist. 1.11), for Macro. But hatred at length prevailed over dissimulation, and Macro, his wife Ennia, and his children, were all compelled to die by a master whose life he had thrice saved, and who owed his empire to the power and preference of his victim. (Tac. Ann. 6.15, 23, 29, 38, 45, 47, 48, 50; Suet. Tib. 73, Cal. 12, 23, 26; D. C. 58.9, 12,13, 18, 21, 24, 25, 27, 28, 59.1. 10; J. AJ 18.6.6, 7; Philo, Legat. ad Caium, p. 994, in Flacc. p. 967.)