Roman jurist and imperial official whose writings supplied one-third of the total content of the Byzantine emperor Justinian I's monumental Digest, or Pandects (completed 533). He was a subordinate to Papinian when that older jurist was praetorian prefect (chief adviser to the emperor and commander of his bodyguard) under Lucius Septimius Severus (reigned 193–211), and he annotated Papinian's works. Afterward Ulpian was master of petitions to the emperor Caracalla, and under Severus Alexander he served as praetorian prefect from 222 until 228, when he was murdered by officers in his command.

Ulpian wrote prolifically on law in a clear, elegant style. Like Papinian, he was an intelligent editor and interpreter of existing ideas rather than an original legal thinker, such as Marcus Antistius Labeo. His major works are the commentaries Libri ad Sabinum (51 books interpreting the civil law; incomplete) and Libri ad edictum (81 books concerning praetorian edicts). Justinian's compilers, headed by Tribonian, drew heavily on these and other treatises and monographs by Ulpian. A work variously called Tituli ex corpore Ulpiani, Epitome Ulpiani, or Regulae Ulpiani is no longer believed to be his.