The Lone Defender is a 1930 American Pre-Code Mascot movie serial starring Rin Tin Tin. This was Mascot's first all sound serial (the second to have any sound at all, after the partial sound in The King of the Kongo). This was Rin Tin Tin's first serial at Mascot, after being dropped by Warner Bros. when they decided animal pictures would not work with "Talkies". He also starred in the later serial The Lightning Warrior, which would be his last appearance. Mascot made a third serial, The Adventures of Rex and Rinty, but that Rin Tin Tin was not the same dog.