Agrippa I (10 BC - 44 AD), referred to in the New Testament as Herod Agrippa (Ἡρώδης Ἀγρίππας), was the tetrarch of the Roman provinces of Galilee and Peraea from 39 to 44. He is most famous for ordering the beheading of James the Apostle. He ruled under the watchful eye of the Romans who had ultimate authority in the region. His tetrachy was subordinate to Emperor Claudius.
King Herod Agrippa I was the grandson of Herod the Great, who had ordered the murder of infants in an attempt to kill baby Jesus in Matthew 2. Herod Agrippa I was the nephew of Herod Antipas, who murdered John the Baptist (Mark 6) and examined Jesus on Good Friday (Luke 23). Herod Agrippa I was also the father of Herod Agrippa II, who heard the defense of Paul before Festus in Acts 25. Herod's sister, Berenice, married the Roman emperor Titus, who destroyed Jerusalem in 70 AD and ended the Jewish Revolt.
Herod Agrippa I himself ordered the beheading of James (Acts 12:2) and then put Peter into prison, although Peter was miraculously freed (Acts 12:3-10). Herod died when he was forming an alliance with other rulers who said he was a god; Herod didn't deny not, and was struck down by an angel of the Lord (Acts 12:20-23). Secular Roman records give a slightly different account, but also record Herod being struck down unexpectedly.