Who was Gonzalo Ruiz de Toledo in The Burial of the Count of Orgaz?

In the painting The Burial of the Count of Orgaz, Gonzalo Ruiz de Toledo is depicted as the deceased patron of the church of Santo Tomé in Toledo, Spain.1

Although he had died approximately 250 years before the oil painting was created by El Greco, the work commemorates his life and the associated legend of his burial. According to this tradition, when he was laid to rest, St. Augustine and St. Stephen miraculously appeared to place his body into the tomb. In the painting, he is shown as a pallid corpse clad in armor being lowered into the ground, while his soul ascends toward Christ in the celestial realm above.1