Shaddam IV was a villain in Dune. He was a Padishah Emperor who ruled in the years prior to the Fremen uprising on Arrakis and the rise of Paul Atreides.He was portrayed by Jose Ferrer in the 1984 film and Giancarlo Giannini in the 2000 Sci Fi Channel (now SyFy) miniseries.
Shaddam felt threatened by his cousin, Duke Leto Atreides who led the House of Atreides on Caladan. A just and honorable man, Leto was loved by his people and was popular amongst the other great houses of the Landsraad - which was the council composed of the leaders of the great houses. Under the tutealage of Thufir Hawat, Gurney Halleck and Duncan Idaho an Atreides army was formed to rival the Sardaukar. Additionally the Spacing Guild was very nervous about Paul Atreides and (in the 1984 film) sent the Guild Navigator Edric to Shaddam to tell him the guild wanted Paul killed, feeling that he was a threat to spice production.
In 10,191 the Emperor pressured Leto to give up his fiefdom on Caladan and take over spice minining and operations on Arrakis, a harsh desert world that was the only known source of spice. Conspiring with the Harkonnen, the traditional rivals of the Atreides, the Emperor had his Sardaukar troops assist in a Harkonnen attack on Arrakis which resulted in the death of Leto and the near destruction of the Atreides army.
What neither the Emperor or Baron Vladimir Harkonnen counted on was Leto's wife Jessica or their son Paul escaping and joining with the Fremen natives of Arrakis. Under Paul's leadership, the Fremen staged an uprising that all but stopped spice production on Arrakis.
Angered by the situation, the Guild traveled to Kaitan and demanded the Emperor restore spice production. The Emperor ordered 50 legions of troops to go to Arrakis, with the intent of committing genocide - the systematic and total destruction of all life on Arrakis. In the conflict that followed the Sardaukar proved to be no match for the Fremen. Baron Harkonnen died at the hands of Leto's daughter Alia, and the Emperor and his daughter Irulan were taken prisoner by the Fremen.
After defeating Feyd-Rathua, Paul explained to the Emperor that he would take Irulan as his wife, and that the Emperor would spend the rest of his days on the Corrino prison planet of Salusa Secundus.