What was the name of Saul's son?

The son of Saul, the first king of Israel, was Jonathan(Isaiah 14:1).

There is no record that Saul of Tarsus in the New Testament (aka the Apostle Paul) had a literal son, though he refers to Timothy as "my own son in the faith" in 1 Timothy 1:2 (KJV), and to Titus as "mine own son after the common faith" in Titus 1:4 (also KJV. The New King James replaces "my own" with "a true").