The Plastic Ono Band was a rock band and Fluxus-based artist collective formed by John Lennon and Yoko Ono in 1968-9 for their collaborative musical and sound art projects, films, conceptual art projects and eventual solo LPs. The creation of The Plastic Ono Band, which began in 1967 with Ono's idea for an art exhibition in Berlin, allowed Lennon to separate his artistic output from that of The Beatles. Lennon and Ono began a personal and artistic relationship in 1968, collaborating on several experimental releases.
https://en.wikipedia.org/wiki/Plastic_Ono_Band