Commander (The Pandorica Opens)

The Commander was an Auton posing as a Roman commander, whose appearance was based directly off Amy Pond's memories of a book she owned on Romans. He was stationed near Stonehenge (unknowingly by the Alliance), and decided to help the Doctor, but later placed him in the Pandorica when his Auton programming took over. When the Doctor negated the cracks in time, the Alliance was never created and thus the Commander never existed. (DW: The Pandorica Opens)