Ida Rentoul Outhwaite, also known as Ida Sherbourne Rentoul and Ida Sherbourne Outhwaite, was an Australian illustrator of children's books. Her work mostly depicted fairies.
Ida was born in Carlton, Victoria, the youngest child of four and second daughter of the Rev. Dr. John Laurence Rentoul, an Irish-born Presbyterian minister and academic, and his wife Annie Isobel.