Grossgrab was a 12th Egyptologist who discovered the tomb of pharaoh Kih-Oskh in 2 June, 1891. He was found mummified with other Egyptologists like Gonzalezi, E.P. Jacobini, M. Trentin and Sandys because Kih-Oskh Brotherhood used the tomb as a secret base.
This character is a reference from character "Professor Grossgrabenstein" from The Mystery of the Great Pyramid by Edgar P. Jacobs.