In a talk at Cambridge Union, Mark Hamill covered the breadth of his acting career. He reminisced about seeing Donald Duck cartoons as a child and coming to the realization - "There are adults whose job it is to sit around making cartoons?!"
When the actor got around to talking about Star Wars, he revealed something interesting - he actually wanted to keep the name Luke Starkiller, as his name was written in the original script. In the first script pages he got, it was a scene between Han Solo and Luke Starkiller, "his name until they changed it - very late!"
"You know, I actually filmed the scene, 'I'm Luke Starkiller, I'm here to rescue you!'" Hamill said. "I got a call sheet that we were going to shoot that scene, and I said, 'we already shot that scene!' They said, 'no, we're going to reshoot it, they've changed your name.' I said, 'Really? What's wrong with Luke Starkiller? Gives him a little moxy!'" he protested. "He could use all the moxy he could get - he's kind of a vapid farmboy, so let's give him a little guts here!"
They went with the change, though, because having "kill" in his name tested poorly with focus groups.
Luke found his moxy eventually, especially with his scenes in Empire Strikes Back. Starkiller found its way back into the saga, too, first in the Legends universe as the name of Darth Vader's secret apprentice, then in Star Wars: The Force Awakens as the planet-sized mobile base of the First Order.