greville was the second son of charles greville, himself a son of fulke greville and descendant of both the duke of beaufort and the baron brooke, and lady charlotte cavendish-bentinck, the daughter of william cavendish-bentinck, 3rd duke of portland and also granddaughter of william cavendish, 4th duke of devonshire. he was the brother of charles cavendish fulke greville, the diarist, and of henry william greville.