Abraham White was the co-founder of the Threshold.
Biography
White met the Pariah when it crashed on Earth, the Pariah offered White power and immortality, Abraham accepted and joined with the Pariah. The duo later created the organisation known as the Threshold.
White died when the Doctor destroyed the Threshold base on the Moon by destroying a Threshold device known as the Eye of Disharmony. (DWM: Wormwood)