Gregory and Herbert are characters in Land of the Dead. They play a modestly important role.
Gregory and Herbert are a pair of bank robbers-for-hire. They appeared in the first Trial, where the Newlydeads were tasked with preventing their escape. Their robbery was foiled, and the two were arrested.
Later, someone paid their (very large) bail, and Gregory and Herbert were released from prison. This distressed them.
The Newlydeads found out why when, for their 10th Trial, they prevented the duo's deaths at the hands of Vicente, who had been hired to kill the two.