Isabella Janet Florentina Summers (born 31 October 1980) is an English musician, songwriter, producer, remixer and member of English indie rock band Florence and the Machine. As well as being the keyboard player for the group, Summers has five co-writing credits on the critically acclaimed, BRIT Award-winning Lungs. Isabella also has three co-writing credits on the album Ceremonials.

When not on tour with Florence and the Machine, Summers spends her time writing, producing and remixing tracks for an array of artists. She is also a founding member of the band The Life, The Love and The Grateful and is in the process of co-writing and producing their debut album.