Red Two was the call sign of the second member of Red Squadron. There were a number of starfighter squadrons with this name, and several beings went by the name Red Two.
In the Clone Wars, Aayla Secura flew a Jedi starfighter as Red Two during the Battle of Kamino.
Keyan Farlander flew as Red Two during his first mission for the Rebel Alliance.
Wedge Antilles used the call sign when he flew for the Alliance during the Battle of Yavin as the XO (Executive Officer, or second in command) of the squadron.
Han Solo was assigned the call sign during a mission to Kamino.
A seemingly unknown Y-wing pilot was called Red Two in the Battle of Endor who was noted for taking a "good shot" by Antilles, who by then was leading the squadron as Red Leader.
During Red Flight's diplomatic mission to Adumar, Tycho Celchu used the call sign.
At the end of Yuuzhan Vong War, Wedge Antilles flying as Red Two, saved Lando Calrissian Lady Luck from pursuing coralskippers.