Wagner (School Reunion)
From Tardis Wiki, the free Doctor Who reference
Mr Wagner was one of Mr Finch's Krillitanes who took over the Deffry Vale High School to solve the Skasis Paradigm and become "gods". All the Krillitanes were destroyed when K9 Mark III blew up a can of their oil.
He differed from the others in that his true Krillitane form was grey. (TV: School Reunion)
Behind the scenes
In a deleted scene, Wagner claimed to a vegetarian. When Mrs Jackson offered him a rat, he claimed to have turned organic.