Then again very little is truely unique. Back in the day, when I wasn't as taken with Farscape as I am now, I pointed out the similarities between D'Argo and Worf, Zhaan and Spock, Aeryn and Seven of Nine, Rygel and Quark. The concept of Farscape was basically taken from Lost in Space.
You're forgetting Buck Rogers - and for that matter, Farscape has a surprising similarity to Lexx conceptually. Almost as if someone saw one of Lexx's pilot movies and decided he could do a better job.
Of course the thing is about Star Wars is it's a direct mashup. It quotes dialogue from old war movies. As a creator Lucas has always been big on nostalgia (aside from Indiana Jones, his homage to the serials of his youth, there's American Graffiti, homage to his youth directly, and even the arty THX begins by comparing its overmedicated protagonist to Buck Rogers...)