Found out that this unnamed LEGO Arc Trooper is actually a named Clone in Season 3 episode 2 (“ARC Troopers”). He is seen for a few seconds and goes by “Hammer”. I
ARC Commander Havoc Custom Star Wars Minifigure – Minifigure Bricks
Amazon.com: LEGO Star Wars Elite Clone Trooper and Commando Droid B 9488 : Toys & Games