Also called Levi, he was a tax collector sitting at a collection booth when Jesus said 'Follow me,' and he immediately got up and followed. He hosted a dinner party for Jesus attended by many tax collectors and sinners. He wrote the first Gospel, directed primarily toward a Jewish audience, emphasizing Jesus as the fulfillment of Old Testament prophecy.
And as Jesus passed forth from thence, he saw a man, named Matthew, sitting at the receipt of custom: and he saith unto him, Follow me. And he arose, and followed him.Matthew 9:9, KJV
Matthew 10:3
Philip, and Bartholomew; Thomas, and Matthew the publican; James the son of Alphaeus, and Lebbaeus, whose surname was Thaddaeus;Matthew 10:3, KJV
Mark 2:14
And as he passed by, he saw Levi the son of Alphæus sitting at the receipt of custom, and said unto him, Follow me. And he arose and followed him.Mark 2:14, KJV
Luke 5:27
And after these things he went forth, and saw a publican, named Levi, sitting at the receipt of custom: and he said unto him, Follow me.Luke 5:27, KJV
Acts 1:13
And when they were come in, they went up into an upper room, where abode both Peter, and James, and John, and Andrew, Philip, and Thomas, Bartholomew, and Matthew, James the son of Alphaeus, and Simon Zelotes, and Judas the brother of James.Acts 1:13, KJV
See how Matthew (Levi) connects to every other figure in Scripture.