Thunderhead is the heavy hitter of the Headshop, and he proved it when he used his massive cannon housed within his android body to blast his way inside the installation holding Bruce Banner prisoner. Needing to recharge his energy before another shot, Thunderhead had to leave it to the rest of his team to initially tackle the soldiers within the base. The jailbreak almost ended in disaster when Banner was critically wounded, but when the Hulk took his place, almost all was well. The Headshop had freed Banner so he could help them take revenge on the evil genius behind their current predicament, the Leader, but Hulk wouldn't have any part of it – especially since the Leader was killed not too long before. When Banner went to leave, Thunderhead put himself between Hulk and the exit. Not completely unexpected, Hulk tossed Thunderhead aside like a rag doll and left their base anyway. Thunderhead could do no more except sit on the sidelines and watch him go.
*Note: Since these events, the Leader has been returned to life, so it remains to be seen if the Headshop will renew their plans of vengeance.