Jill Lovelace is a fictional character in the Doom novels. She first appears in Doom: Hell on Earth.
Not much is known about Jill's past outside of a few hints she lets slip. At 14 years old, she is the youngest human character in the series to have an impact on the story. She is an orphan; her parents were killed in the invasion, and she was taken under the wing of the President of the Mormon Council in Salt Lake City, with concurrent apprehension about it on her part. At first, she remained rather aloof and quiet to her new colleagues, to the point where she lied about her last name being "Hoerchner".
Jill is a brilliant computer hacker, and her skills with her "CompMacPro" portable computer is essential to completing the Los Angeles mission. However, her skills also got her in trouble in the past, warranting jail time on her behalf.
Jill was not warmly accepted by Flynn and Arlene upon their first meeting; neither of them were impressed or pleased with the President on his insistence on having her tag along with them, and her sarcastic attitude certainly made her few friends with anyone outside of Albert. Throughout the L.A. mission, her naivety on the battlefield caused a few problems for the more well-to-do Marines, but she managed to keep it together long enough to survive a revenant rocket attack, kill her first imp, and cause the destruction of a cyberdemon and a spider mastermind on the train en route to L.A. Despite her young age, she is shown throughout the mission to actually be able to drive a stick-shift truck and pilot an airplane (with the help of the CompMac). As time and the mission progressed, the Marines, most notably Flynn, began to warm to her, and she to them, with a one-sided romantic crush on Flynn developing.
Jill was instrumental in "hacking" into the computerized brain of Ken Estes, the "cybermummy", and find out information on the invaders pertinent to their defeat. Said information would be a boon to the survivors in Hawaii (their goal upon the success of the L.A. mission), and Jill would be Ken's most constant companion upon his recovery.
In "Infernal Sky", Jill is sent on one last mission with Flynn, Arlene, Albert, and Captain Hidalgo back to the States in order to secure their safe passage into space to meet Sears and Roebuck, but, to her dismay, she was to stay behind on Earth while her friends journeyed into space. Destroyed, she verbally strikes back against them, but a somewhat calm lecture on Arlene's part, about how they may never see her again but love her all the same, sets her straight. Jill departs to head back to the submarine to take her back to Hawaii, but an error on her part causes her to lose her way and end up stranded in L.A. enemy territory. During this time, she comes across two human traitors in an abandoned drug store and, unbeknownst to them, kills them with cynogen gas. She then bids her friends a broken-hearted goodbye.
During the events in "Endgame", it has been reported that Jill survived and fought in the Doom Wars/subsequent invasion of the Freds. She then returned to Salt Lake City/Grad and helped recreate society, as well as write a number of books chronicling the Doom Wars, including the rivalry between the Hyperrealists and the Deconstructionists. Two of those books were known as "Knee-Deep in the Dead" and "Hell on Earth", necessary textbooks for the new world. She was Albert's last companion up to his death and continued her work until she passed away at a ripe old age.
When Flynn and Arlene return back to Earth over 400 years later, they return to Salt Lake Grad and find that Jill's 15-year old conscious has been placed into the computer systems of the stronghold in the form of a hologram and she had herself cloned at that same age. Dubbed "Sleeping Cloney", she left vague instructions on how to bring her back to life with "one single kiss".