Colbi Gannett Height Height. 4′ 9″ (1.45 m) Colby Gannett is an American actress best known for her performances in The New Mutants (2020), Castle Rock (2019) and Skin (2018). She has played a variety of roles ranging from young Illyana in The New Mutants to young Joy Wilkes in Castle Rock. TV viewers met Colby in the role of Lily in Olive Kitteridge. Colby Gannett was born in 2008 in Los Angeles, USA. As of 2022, Colby Gannett’s age is 14 years old. Check out below for more information on Colbi Gannett. This page will shed light on Colby Gannett’s biography, wiki, age, birthday, family details, affairs, controversy, caste, height, weight, rumors, little-known facts and more.