Which official helped compile Justinian's Digest and Code?

The official who helped compile Justinian’s Digest and Code was Tribonian, a jurist and senior adviser to Emperor Justinian I. He directed major stages of the Byzantine effort to organize and reform Roman law.

Tribonian was appointed to Justinian’s first legal commission in 528, which produced the initial Codex Justinianus in 529. He later supervised the commission that assembled the Digest, a vast collection of excerpts from earlier Roman legal writers. The Digest and the Institutes, a textbook for beginning law students, were issued in 533; a revised edition of the Code followed in 534.

Together with Justinian’s later laws, these works formed the Corpus Juris Civilis, often called the Code of Justinian. The compilation preserved centuries of Roman legal thought and eventually became one of the foundations of civil-law systems in Europe and beyond.

Tribonian was more than a compiler. He served as quaestor of the sacred palace, drafted imperial legislation, and helped shape legal education. Political enemies accused him of corruption during the Nika riots, temporarily costing him his office, but Justinian restored him. He died in 542, possibly during the plague.