St. Andrew was among the first disciples called by Jesus. In fact, in the Orthodox tradition, Andrew has the title "Protokletos" which means "first-called." This stems from the Gospel of John in which Andrew is described as a disciple of John the Baptist. John points out Jesus to Andrew who, after meeting him, then brings his brother Peter to Jesus. This is the first of several times in the Gospels in which Andrew acts as a middleman by bringing individuals or groups to Jesus. Other examples include Andrew bringing the boy with the loaves and fishes to Jesus and bringing a group of Greek tourists to Jesus.
Like his brother, Andrew was born in Bethsaida and was a fisherman by trade. Not much is mentioned about Andrew in the Gospels beyond those instances in which he serves to introduce others to Jesus. However, there are many traditions about his activities following the Ascension. Andrew is said to have preached in Scythia, Ukraine, Romania and Russia. He founded the See of Byzantium (later renamed Constantinople) in AD 38. Finally, he was martyred by crucifixion in Patras, Greece. There is some question over the shape of the cross, with some maintaining it was a Latin cross and other that it was a crux decussata (X-shaped cross) now commonly called St. Andrew's Cross.
In addition to these traditions, there are several legends that have developed around St. Andrew. One is that he founded the Georgian Church in the Caucasus region. He is also said to have preached up the Dnieper River and erected a cross at the future location of Kiev, Ukraine on the spot where St. Andrew's Church of Kiev now stands.
Perhaps the most famous of St. Andrew's legends involved the nation of Scotland. Traditionally, it is believed that the relics of St. Andrew were brought to Scotland in the 8th century by Regulus. These relics were given to the Pictish king Oengus mac Fergusa. Later, in AD 832, Oengus II led an army of Picts and Scots against the Angles. He vowed to appoint Andrew patron of Scotland if they won. On the morning of the battle, clouds appeared to form the shape of an X in the sky and the Scots were victorious in spite of being vastly outnumbered. As a result, St. Andrew was named the patron of Scotland, and the white X-shaped clouds against the blue sky became the basis for the Scottish flag.