Isabella Janet Florentina Summers is an English musician, songwriter, producer, remixer and composer. She is a founding member of English indie rock band Florence and the Machine.

Florence and the Machine are an English indie rock band that formed in London in 2007, consisting of lead vocalist Florence Welch, keyboardist Isabella Summers, guitarist Rob Ackroyd, harpist Tom Monger, and a collaboration of other musicians. The band's music has received acclaim across the media, especially from the BBC, which played a large part in their rise to prominence by promoting Florence and the Machine as part of BBC Music Introducing. At the 2009 Brit Awards they received the Brit Awards "Critics' Choice" award. The band's music is renowned for its dramatic, eccentric production and Welch's powerful vocals.