D. Allen

Sergeant Dennis Allen was a Brotherhood of Steel member, probably one of the members of Roger Maxson's original team.

Background
In 2134, a faction led by Allen gained strength, and they urged the Elders to let them explore the ruins of West Tek to the southeast (called the Glow after it was hit by a nuclear bomb) for artifacts. The Elders refused, so Allen and his separatist group split away from the Brotherhood of Steel, taking some technology and weapons with them. Other members of the team included Soto, Jensen and Camarillo.

They made it to West Tek Research Facility after 20 days. The radiation levels began to shoot up as soon as the giant crater was in sight. They concluded that with their armor and Rad-X supplies they'd be fine for a least a day of exploring and that the technology they had the potential of recovering was worth it.

They climbed down the crater to the first level and as there wasn't much of value on this level, they pushed on. Unfortunately for them, the security sensors had been burned out on the first two levels, but not on the third. Jensen was killed before he knew what had happened. Allen tried to regroup, but only Soto and Camarillo made it back up here to the first level with him. All three of them eventually died because of a power armor air filtration failure. Before he died, Allen logged what happened to the expedition into a holodisk which was later found by the Vault Dweller.

Appearances
Allen appears only in the first Fallout as a corpse.