An Australian, Sumner was probably best known to American audiences as Lieutenant Pol Treidum, an Imperial officer who appeared in the original Star Wars film. Though he’s never named onscreen, Treidum is the guy working in the Death Star hangar who notices that a pair of Stormtroopers have gone missing while searching through the just-captured Millennium Falcon, prompting the weirdly memorable line, “TK-421, why aren’t you at your post? TK-421, do you copy?” Later, as the heroes begin their mission to rescue Princess Leia, he is attacked—and probably killed—by Chewbacca, sparing him from having to blow up along with everyone else when the Death Star is destroyed. In 1999, Sumner reprised his role in the Star Wars fan film The Dark Redemption.
When he started filming Star Wars, Sumner said he was “absolutely amazed” by the elaborate Death Star set, and while hanging around on his first day, a man wearing “an old white shirt and grey pants” started talking to him. He thought this man was an accountant, but before he could ask for his name, a crew member walked up and acknowledged him as “Mr. Lucas.” That was Sumner’s first meeting with George Lucas, and considering how small his role in Star Wars is (even if it has become iconic its own way over the years), he probably didn’t get a ton of chances after that.
Sumner was born in 1942, and he worked as a high school teacher before he became an actor. Once he did, though, he worked on shows and movies like Spyforce, Cluedo, Heartbreak High, and Ned Kelly—where he appeared alongside Mick Jagger.
According to the Sydney Morning Herald obit, Sumner once joked that “TK-421, do you copy?” would be the epitaph on his tombstone.