Julian Casablancas favorite philosopher, whose work, Casablancas claims, held truth as an important standard value. He recognizes Paul Robeson as someone who used his musical platform to help further his serious political intrigue and as someone who, therefore, serves as a role model for politically engaged musicians. Casablancas has been a guest on the Russian sponsored program "Redacted Tonight", as well as included its host, Lee Camp, as an opener for a Voidz show in Houston, Texas in October 2018. Casablancas, along with the Strokes, provided vocals on a cover of Marvin Gaye's "Mercy Mercy Me (The Ecology)" with Joshua Homme on
Julian Casablancas drums and Eddie Vedder on backup vocals. The cover was released in 2006 as the B-side to "You Only Live Once". Casablancas also provided bass guitar and backing vocals on Albert Hammond, Jr.'s "Scared" on his solo album "Yours to Keep". He subsequently played a Casio guitar and provided backing vocals on "Sick, Sick, Sick" by Queens of the Stone Age. In 2008, he recorded a song with Santigold (then known as Santogold) and Pharrell of N*E*R*D called "My Drive Thru" for a Converse advertising campaign. During his solo phase, he recorded "Boombox" with Andy Samberg, Jorma Taccone, and Akiva