Often identified with Nathanael, who was brought to Jesus by Philip. Initially skeptical ('Can anything good come from Nazareth?'), he was immediately impressed when Jesus said he had seen him under the fig tree before Philip called him. He declared Jesus to be 'the Son of God, the King of Israel.'
Philip, and Bartholomew; Thomas, and Matthew the publican; James the son of Alphaeus, and Lebbaeus, whose surname was Thaddaeus;Matthew 10:3, KJV
Mark 3:18
And Andrew, and Philip, and Bartholomew, and Matthew, and Thomas, and James the son of Alphaeus, and Thaddaeus, and Simon the Canaanite,Mark 3:18, KJV
John 1:45
Philip findeth Nathanael, and saith unto him, We have found him, of whom Moses in the law, and the prophets, did write, Jesus of Nazareth, the son of Joseph.John 1:45, KJV
John 1:49
Nathanael answered and saith unto him, Rabbi, thou art the Son of God; thou art the King of Israel.John 1:49, 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 Bartholomew connects to every other figure in Scripture.