Bruce Willis wasn’t the first choice for Butch
Much like Daniel Day-Lewis, Bruce Willis was desperate to play Vincent Vega. But when Tarantino cast Travolta, he really liked Willis for the role of Butch Coolidge, but he had a problem; the role had been promised to Matt Dillon. So, when the script got sent to Dillon and he said he needed to sleep on it, Tarantino took it away from him and gave it to Willis.
The role ended up revitalizing his career too, and gave the film the star power it needed.