Doctor Who (season 11)  The eleventh season of British science fiction television series "Doctor Who" began on 15 December 1973 with the serial "The Time Warrior", and ended with Jon Pertwee's final serial "Planet of the Spiders". The season's writing was recognized by the Writer's Guild of Great Britain for Best Children's Drama Script.   Jon Pertwee makes his final appearance as the series lead in "Planet of the Spiders", although he would reprise the role of the Third Doctor in the 20th anniversary special episode, "The Five Doctors". Elisabeth Sladen makes her first appearance as Sarah Jane Smith in "The Time Warrior". Tom Baker makes his first uncredited appearance as the Fourth Doctor in Part 6 of Planet of the Spiders, when Jon Pertwee's Doctor dies and regenerates into the Fourth Doctor. Nicholas Courtney and John Levene continue their roles of Brigadier Lethbridge-Stewart and Sergeant Benton, while Richard Franklin makes his final regular appearance as Captain Yates in "Planet of the Spiders"  Alan Bennion makes his third and final appearance in the series as an Ice Warrior, portraying Lord Azaxyr in "The Monster of Peladon". This season was the last to have Barry Letts as Producer and Terrance Dicks as Script Editor, ending the relationship that had gone through the whole of Jon Pertwee's tenure as the Doctor. It saw the introduction of a new logo that would be used nearly throughout the fourth Doctor's era, as well as the new companion Sarah Jane Smith and the alien race, the Sontarans. Episode one of "The Time Warrior" saw the first appearance of the iconic diamond-shaped "Doctor Who" logo. This would be used throughout the Third Doctor's final season and almost through the Fourth Doctor's tenure before retiring in part four of "The Horns of Nimon" (not including the unbroadcast and incomplete serial "Shada" which would have followed "The Horns of Nimon"). The entire season was broadcast from 15 December 1973 to 8 June 1974.