Platorius Nepos, Aulus (fl. 119–c. 125), Roman governor of Britain, whose full name was Aulus Platorius Nepos Aponius Italicus Manilianus Gaius Licinius Pollio, was the governor of the Roman province of Britain between 122 and c.125. He is chiefly known, in consequence, as the person in charge of construction work on Hadrian's Wall. Sources for his life and career are few, but he is mentioned in the Historia Augusta (ed. Magie), which contains a brief biography of the emperor Hadrian, and his name is found on Roman inscriptions from Hadrian's Wall. His career in Roman public and military service is also detailed on a dedication set up in his honour in Aquileia (near Trieste), in northern Italy. He held the highest office at Rome—the consulship—before becoming governor of the province of Lower Germany in 119, the post he held before his governorship of Britain.

Platorius Nepos was appointed to Britain in July 122, in succession to Quintus Pompeius Falco, and was entrusted by the emperor Hadrian with the task of overseeing construction of the military frontier installations now known as Hadrian's Wall. These consist of a stone wall, originally from Pons Aelii (now the centre of Newcastle) running westwards to the crossing of the River Irthing (some 45 miles), beyond which point the wall was built of stacked turf to its terminal point on the Solway Firth at Maia (Bo'ness). It was also extended eastwards in stone from Pons Aelii to Segedunum (Wallsend). The wall was accompanied by a ditch, and small defended gateways (known as milecastles) spaced more or less regularly at each Roman mile, together with pairs of further towers (known as turrets) evenly distributed between the milecastles. At a slightly later stage, Roman forts, providing garrison bases for troops stationed on the wall, were added to its line, and a flat-bottomed ditch flanked by a pair of mounds (now known as the vallum) was dug behind the wall for virtually the whole of its length.

Platorius Nepos's oversight of this work is commemorated by a number of surviving inscriptions from milecastles both on the stone- and the turf-built portions of the wall, and from other inscriptions recording construction of the military forts added slightly later. It is not certain to what extent Platorius Nepos can be termed the architect of Hadrian's Wall, but he was clearly entrusted with the responsibility of translating the vision of this frontier (which may have been the emperor Hadrian's own) into reality on the ground. The term of Platorius Nepos's governorship in Britain came to an end, possibly abruptly, in 124 or 125, with the works still not completely finished, and with aspects of frontier design and its implementation still evolving.

Platorius Nepos is said at one stage to have been considered by Hadrian as a possible successor to him as emperor, but latterly fell out of favour for reasons which cannot be determined, but which may relate to an inability to control the extravagant cost of construction of the Hadrianic frontier in the north of Britain. After holding the governorship of Britain, Platorius Nepos faded out of public life. At his death (date unknown) a statue was erected in his honour by the town council of Aquileia. This gives full details of his career in public life, and shows the junior posts he held, in military and civilian service, before attaining the consulship and subsequent posts as consular governor in Germany and Britain. The town councillors of Aquileia (the decurions) dedicated this inscription to a man they described as their 'patron'.