The story of Nicodemus is told in Saint John's Gospel (John 3: 1-21). Nicodemus was a member of the ruling council in Jerusalem, the Sanhedrin. He went secretly to see Christ at night. Christ told him that to enter the kingdom of Heaven it is essential to be 'born again', by which he meant a spiritual re-birth by baptism.
Nicodemus appeared again, after the Crucifixion, when he brought myrrh and aloes to anoint Christ's body before the Entombment and helped Joseph of Arimathaea to bury him (John 19: 39). He is usually depicted in these scenes as an elderly man.