Zachary "Zack" Uriah Addy, Ph.D, is a fictional character in the television series Bones. The character is portrayed by Eric Millegan and was introduced as Dr. Temperance Brennan's young assistant at the beginning of the series before he received his doctorate in forensic anthropology in season 2. Millegan was a main character throughout seasons 1 to 3, appearing in all episodes. Since then, he has made guest appearances in season 4, season 5, the season 11 finale, and had a recurring role in the series' final season. In the penultimate episode of the series, "The Day in the Life", Zack is exonerated for the murder that left him incarcerated at the end of season 3.

Bones is an American police procedural comedy drama television series created by Hart Hanson for Fox. It premiered on September 13, 2005, and concluded on March 28, 2017, airing for 246 episodes over 12 seasons. The show is based on forensic anthropology and forensic archaeology, with each episode focusing on a Federal Bureau of Investigation (FBI) case file concerning the mystery behind human remains brought by FBI Special Agent Seeley Booth to Temperance "Bones" Brennan, a forensic anthropologist. It also explores the personal lives of the characters. The rest of the main cast includes Michaela Conlin, T. J. Thyne, Eric Millegan, Jonathan Adams, Tamara Taylor, John Francis Daley, and John Boyd.