Tim Yorba

Corporal Tim Yorba was a Sentinel that participated in Operation Iron Fist that took place in South Dakota on November 28, 1951. His team was led by Lt. Nathan Hale and their mission was to infiltrate a Chimeran base and take one of the feul cells. To infiltrate the base the Sentinels used 3 Stalkers to sneak by the Chimeran defenses. The Stalkers were also used to destroy the 4 gun towers defending the base. Yorba placed demolition charges on the Stalkers as the Sentinels prepared to enter the base. During the infiltration Yorba was armed with an Chimeran Auger. He also used explosives to open the doors leading into the base. Yorba was hit during the battle on the roof of the base, but was able to continue due to his regenerative abilities, and he survived to complete the mission. It is unknown what happened to him after the mission.

Yorba is described as having black hair, brown skin and a round face by Nathan Hale. Hale also describes Yorba as being very cheerful, which is evident when he blows open the doors to the Chimeran base and says '' "Open sesame!" ''

Yorba is referred to as Echo-Four several times during the mission, which means that he was likely an early member of Sentinel Echo Team.