Who was the man that pierced Jesus on the cross?

The Bible says very little about this person; in fact, he is only mentioned in one verse, John 19:34:

…one of the soldiers pierced his side with a spear, and at once there came out blood and water.

So, we know that he was a Roman soldier (cp. John 18:31; 19:1-2,34), but that’s the only information we have.