Ian Kelliher is the current CEO and president of the Union Aerospace Corporation.
A coldly precise person, Kelliher is very controlative with the UAC activities on Mars, Earth and the Moon. He usually acts authoritatively with most of the people of the UAC, especially with General Hayden and is considered the most powerfull person on Earth, having "more money than God" and even more important than the president of the United States. Kelliher also has a strange and cold relationship with his father, Thomas Kelliher, the founder of the UAC.
He is one of the few mainly characters in the Doom universe which is only mentioned but never appears on the games. He is mentioned in one of the e-mails on Doom II RPG and has a biography (with a picture) at the "official site" of the UAC from Doom RPG. He is also one of the main characters in the Doom 3 novels.
Behind the scenes
Ian Kelliher is the UAC chairmen in the 2144-2145 period covered by the novels. He is president/CEO at the time Doom/Doom II RPGs take place. The website for Doom RPG may suggest that Doom RPG takes place after Doom 3, but its unknown if it takes places before or after Doom 1 and II. Other than a few vague references might imply Doom 1 and II takes place later (or at least just simply nods to the classic games in general).