Who was the oldest Apostle?

Peter was the eldest apostle by age and by status. He was the first that Christ came across when He began his ministry. The fact that he was the eldest apostle, by age and status, is evidenced by his correct answer to Christ's searching question later: "Who am I", to which Peter responded, "You are the son of God". Peter was old enough to answer wisely, and was blessed and charged with the keys to the gates of Heaven for his timely affirmation of the Messiah. St. Peter loved Christ more than any other apostle, but Christ loved St. John more, indicating that John perhaps was the youngest. Incidentally Peter is depicted in Christian art work through the ages as grayer haired than the rest, as is God.

Here is the scripture of reference:

Joh 1:42 And he (Andrew) brought him (Peter) to Jesus. Jesus looked at him and said, "You are Simon son of John. You will be called Peter (Gk., Aramaic Cephas)."

Another perspective:There is only one honest answer to your question: We don't know. The Bible doesn't give us the apostles' ages, or tell us what they looked like.