The Gospel of Luke is the third of the New Testament's four canonical Gospels. It tells of the origins, birth, ministry, death, resurrection, and ascension of Jesus. Together with the Acts of the Apostles, it makes up a two-volume work which scholars call Luke–Acts, accounting for 27.5% of the New Testament.

The text is anonymous, not naming its author. Perhaps most scholars think that he was a companion of Paul, but others cite differences between him and the Pauline epistles. In the popular Two-source hypothesis, Luke used the Gospel of Mark and a hypothetical collection called Q, with unique material often called L, though alternative hypotheses that posit the direct use of Matthew by Luke or vice versa without Q are increasing in popularity within scholarship. Luke follows Mark closely compared to other ancient historians’ usage of sources, though the parallels and variations of the Synoptic gospels are typical of ancient historical biographies. If and to what extent the author made own amendments is unclear. The most common dating for its composition is around AD 80–90. The earliest witnesses for the Gospel of Luke are the Alexandrian and the revised western text-type.

Following the preface addressed and the birth narratives of John and Jesus, the gospel begins in Galilee and moves gradually to its climax in Jerusalem. Luke espouses a three-stage "salvation history" starting with the Law and the prophets, the epoch of Jesus, and the period of the church. The gospel's Christology can be understood in light of the titles given to Jesus and its Jewish and Greco-Roman context. The Holy Spirit also plays a more prominent role compared to other Christian works, forming the basis of the early Christian community.

Autographs (original copies) of Luke and the other Gospels have not been preserved; the texts that survive are third-generation copies, with no two completely identical. The earliest witnesses (the technical term for written manuscripts) for the Gospel of Luke fall into two "families" with considerable differences between them, the Western and the Alexandrian text-type, and the dominant view is that the Western text represents a process of deliberate revision in the second century, as the variations seem to form specific patterns.

The fragment 𝔓⁴ is often cited as the oldest witness. It has been dated from the late 2nd century, although this dating is disputed. Papyrus 75 (= Papyrus Bodmer XIV–XV) is another very early manuscript (late 2nd/early 3rd century), and it includes an attribution of the Gospel to Luke. The oldest complete texts are the 4th-century Codex Sinaiticus and Vaticanus, both from the Alexandrian family; Codex Bezae, a 5th- or 6th-century Western text-type manuscript that contains Luke in Greek and Latin versions on facing pages, appears to have descended from an offshoot of the main manuscript tradition, departing from more familiar readings at many points. Codex Bezae shows comprehensively the differences between the versions which show no core theological significance.

The gospel of Luke and the Acts of the Apostles make up a two-volume work which scholars call Luke–Acts. Together they account for 27.5% of the New Testament, the largest contribution by a single author, providing the framework for both the Church's liturgical calendar and the historical outline into which later generations have fitted their idea of the story of Jesus.

The author is not named in either volume, but he was educated, a man of means, probably urban, and someone who respected manual work, although not a worker himself; this is significant, because more highbrow writers of the time looked down on the artisans and small business-people who made up the early church of Paul and who were presumably Luke's audience. According to a Church tradition first recorded by Irenaeus (c. AD 130 – c. AD 202) he was the Luke named as a companion of Paul in three of the Pauline letters, but a scholarly consensus emphasizes the differences between the portrayal in Acts and the Pauline epistles, though this has been challenged in recent years. The author of the Gospel of Luke clearly admired Paul, he does not thoroughly represent Paul's key theological points. Many modern scholars therefore doubt that the author of Luke-Acts was the physician Luke, and critical opinion on the subject was assessed to be roughly evenly divided near the end of the 20th century. Most scholars maintain that the author of Luke-Acts, whether named Luke or not, met Paul at some point.

The interpretation of the "we" passages in Acts as indicative that the writer relied on a historical eyewitness (whether Luke the evangelist or not), remains the most influential in current biblical studies. Objections to this viewpoint, among others, include the claim that Luke-Acts contains differences in theology and historical narrative which are irreconcilable with the authentic letters of Paul the Apostle.