Gill Donovan is the identical twin brother of Will. He was described as a smart, humorous boy who excelled in math and science, and enjoyed making jokes with his brother and those around him. He was eliminated in the first round of The Testing, and was later found at a genetics facility in Decatur Colony, where he was being experimented on. He was then reuinited with Will, and they pursued to make jokes together like they always had with Cia.
- Gill's name was misspelled as "Gil" in Graduation Day.