Goodnight Julia is a song from Cowgirl Ed.
A different version of the song also featured during the Titan War, when Gren approached Vicious while he was listening to the music box that played the song. Starting up a conversation, he asked for the name of the song and if he could play it on his saxophone back home. Vicious answered him and, to Gren's surprise, gave him the box. Julia later revealed to Gren that the music box contained a solar transmitter. Gren mentioned the song to Spike as he described his encounter with Julia.