Zack Allan, played by Jeff Conaway, is a character in the universe of the science-fiction television series Babylon 5.

Allan was the second aide to B5 Chief of Security Michael Garibaldi from 2259-2261. Following Garibaldi's resignation as chief of security in 2261, Allan was appointed Chief of Security. He held the position for many years; except for a brief stint back on Earth, he remained there until the station was decommisioned in 2281.