Greek Loukas (probably short for Lucanus). The "beloved physician" (Colossians 4:14), a Gentile by background — the only non-Jewish author of any New Testament book — and the writer of the longest portion of the NT after Paul: the Gospel of Luke (24 chapters) and the Acts of the Apostles (28 chapters) together comprise roughly 27% of the New Testament by word count. Luke was a traveling companion of Paul during the latter half of Paul's missionary career (the "we" passages of Acts begin at 16:10) and was with him in his final imprisonment: "Luke alone is with me" (2 Timothy 4:11).
Luke is the historian's historian. He opens his Gospel by announcing his method: "Inasmuch as many have undertaken to compile a narrative of the things that have been accomplished among us, just as those who from the beginning were eyewitnesses and ministers of the word have delivered them to us, it seemed good to me also, having followed all things closely for some time past, to write an orderly account for you, most excellent Theophilus" (Luke 1:1-4). His distinctives: (1) Careful sourcing — he interviewed eyewitnesses and used existing written accounts; (2) Literary Greek — Luke's prose is the most polished in the NT; (3) Universal scope — his genealogy of Jesus goes back to Adam (not just Abraham as Matthew's does), emphasizing Jesus as the savior of all humanity; (4) Attention to the marginalized — women, the poor, Samaritans, Gentiles, tax collectors, and the sick all receive prominent treatment; (5) Prayer and the Spirit — Luke highlights Jesus praying at every major juncture and records more Holy Spirit references per chapter than any other Gospel; (6) Acts as continuation — Luke writes a two-volume work; the Gospel tells what Jesus began to do, and Acts tells what He continued through the Spirit-filled Church. Without Luke we would know nothing of the shepherds at Bethlehem, the Prodigal Son, the Good Samaritan, the Emmaus road, Zacchaeus, the thief on the cross's repentance, or most of the book of Acts.