Annas was the father-in-law of Caiaphas. He is mentioned in the Bible at:

Luke 3:2 "Annas and Caiaphas being the high priests, the word of God came unto John the son of Zacharias in the wilderness."

John 18:13 "And led him away to Annas first; for he was father in law to Caiaphas, which was the high priest that same year. "

John 18:24 "Now Annas had sent him bound unto Caiaphas the high priest."

Acts 4:6 "And Annas the high priest, and Caiaphas, and John, and Alexander, and as many as were of the kindred of the high priest, were gathered together at Jerusalem."