In the New Testament
Andrew, Simon Peter's brother, was from Bethsaida on the Sea of Galilee and worked as a fisherman alongside Peter before Jesus called them both (Matthew 4:18–20; Mark 1:16–18). John's Gospel gives a different, likely complementary account: Andrew was first a disciple of John the Baptist, and after hearing the Baptist identify Jesus as "the Lamb of God," Andrew followed Jesus and then brought his brother Simon to meet him, saying "We have found the Messiah" (John 1:35–42) — making Andrew, in a real sense, the first person in the Gospels to actively evangelize someone else. He appears again bringing the boy with five loaves and two fish to Jesus before the feeding of the five thousand (John 6:8–9), and again bringing a group of Greek God-fearers to Jesus near the end of his ministry (John 12:20–22) — a small but consistent pattern of Andrew as a connector, someone who brings others rather than someone who speaks the memorable lines himself.
Later mission and martyrdom tradition
Early church tradition, recorded by Eusebius drawing on Origen, holds that Andrew preached in Scythia (the region north of the Black Sea, roughly modern Ukraine and southern Russia) — the basis for later claims of Andrew as patron of Russia and Ukraine. Byzantine and Greek tradition also places his ministry in Asia Minor and Greece, particularly the city of Patras (Patræ), where he is said to have been martyred around AD 60, traditionally by crucifixion on an X-shaped cross (a "saltire") — though this specific cross-shape detail appears late in the tradition (it's not attested before the Middle Ages) and is likely a later devotional addition rather than a first-century historical detail. The saltire nonetheless became Andrew's enduring symbol, appearing on the flags of Scotland and (combined with others) the United Kingdom, since medieval tradition also claims some of Andrew's relics were carried to what became St Andrews in Scotland, making him Scotland's patron saint.
Why it matters
Andrew's consistent role — never the headline figure, always the one quietly bringing someone else to Jesus — is a useful corrective if your picture of significant discipleship defaults to visible leadership or dramatic conversion stories. The first recorded act of personal evangelism in the Gospels belongs to a fisherman whose main recorded contribution was telling his brother "come and see," and whose brother then became the more famous apostle.