There are no surviving writings strictly contemporary to Jesus' lifetime (c. 4 BC–30 AD) that mention him. The earliest non-Christian references come later, including two from Jewish historian Flavius Josephus in "Antiquities of the Jews" (c. 93–94 AD).
1. On James (Book 20, Ch. 9): "...the brother of Jesus, who was called Christ, whose name was James..."
2. Testimonium Flavianum (Book 18, Ch. 3): "About this time there lived Jesus, a wise man, if indeed one ought to call him a man. For he was one who performed surprising deeds and was a teacher of such people as accept the truth gladly. He won over many Jews and many Gentiles. He was the Christ. When Pilate, upon hearing him accused by men of the highest standing amongst us, had condemned him to be crucified, those who had in the first place come to love him did not give up their affection for him. On the third day he appeared to them restored to life, for the prophets of God had foretold these things and a thousand other marvels about him. And the tribe of the Christians, so called after him, has still to this day not disappeared."
Scholars generally view the James reference as authentic. The Testimonium is seen as partially authentic but with likely Christian interpolations (e.g., resurrection claim). Other later sources include Tacitus (c. 116 AD) and Pliny the Younger (c. 112 AD).