"That Lady" is a song by the Isley Brothers, made famous in 1973 when it was reworked in a funk rock style. It was originally performed as "Who's That Lady?" in a classic R&B vocal style by the Isley Brothers in 1964, inspired by the Impressions. In 1973, the core Isley Brothers vocal trio had recently expanded, picking up guitarist Ernie Isley, bassist Marvin Isley and keyboardist Chris Jasper to... Wikipedia