R5-D4/Legends

R5-D4 was the name of the red droid that Luke Skywalker's Uncle Owen Lars originally intended to purchase instead of R2-D2. Within seconds of the purchase, R5-D4's motivator malfunctioned, and the otherwise shifty Jawas let Owen have R2-D2 instead. Although a minor incident, had R5-D4's motivator lasted even minutes longer, the entire Star Wars story would not have unfolded.

Some say R5-D4, not wanting to split up the duo of R2-D2 and C-3PO, blew his own motivator. Some say R2-D2 himself had tampered with it. The truth may never be known, as R5-D4 is believed to have been destroyed along with the Jawa Sandcrawler.

R5-D4 has a brief cameo in Attack of the Clones.