Mercy Graves' past is unclear before she came to work for Lex Luthor. Whatever her origin, she found work as his bodyguard and assistant, and has remained loyal to him for many years.
Mercy Graves was created by Bruce Timm and Paul Dini as part of Superman: the Animated Series.
In her original medium, Graves was a brunette of average strength and above-average intelligence. She was introduced as a former leader of a gang of thieves, who had stolen Luthor's briefcase. Impressed, he offered her employment, which she took. Their relationship has been implied to be more than platonic in nature.
In the comics, Graves became a blonde, and is an Amazon, having above-average strength, agility, and other attributes common to Amazons. Dialogue in the comics supported this version of her past, and it was confirmed in Cry for Justice.
Major Story Arcs
No Man's Land
Graves makes her first in-comics appearance in the No Man's Land storyline, where she is the bodyguard of Luthor.
Secret Files: President Luthor
Graves and another bodyguard, Hope, are protecting Luthor when they encounter Circe, who they claim they can recognize regardless of the disguise she adopts. Circe turns the pair into birds, though they are eventually returned to human form
Graves appears alongside Luthor throughout 52. She is wounded after shooting at Steel, who attacks Luthor at a party. The bullets she fires at him are returned at her via magnetic manipulation; the superheated metal burns her hand and wrist. She reappears soon after, apparently healed and still working for Luthor.
Taking the super name "Vanilla," Graves joins Infinity, Inc., wearing a special mask to prevent Luthor and others from her regular life from recognizing that it's her. She leaves the group shortly after nearly beating a man to death, realizing that she isn't cut out to be a hero.
Powers and Abilities
As an Amazon, Graves has superhuman strength, agility, speed, reflexes and endurance, as well as increased longevity. She is a very skilled hand-to-hand fighter, and shows proficiency with a wide variety of weapons.
In Other Media
Similarly to Harley Quinn, Graves originated in the DCAU, and immigrated to comic continuity after her character proved popular. She was originated in Superman: the Animated Series, in the episode "A Little Piece of Home". In the series, she was Lex Luthor's chauffeur and bodyguard, and also acted as his personal assistant. After Luthor was revealed as a supervillain and had to leave LexCorp for prison, she was handed control of the company, a fact revealed in the Justice League episodes "Tabula Rasa" and "Tabula Rasa Part II". Though dismissive of Luthor's plight when he comes to her for help, and full of her own achievements as head of the company, she proves ultimately loyal, and aids him in evading the Justice League. This loyalty doesn't extend much further, however, and she refuses to speak with him after he is arrested. She also appears in the Justice League Unlimited episode "Clash," again working for Luthor. She is played in all her DCAU appearances by Lisa Edelstein.
Graves appears in the episode "The Superman/Batman Story, Part One" as Lex Luthor's right-hand woman. She appears to be Eurasian in origin. She fights Batman and Robin, but is defeated after Luthor betrays her. She is played by Gwendoline Yeo.
Graves appears as Luthor's assistant and bodyguard in the episode "Targets". She is apparently a cyborg, or possibly an android, as she has an energy weapon concealed in her right arm, and possibly other modifications that go unexplored in the episode. She does not speak during her appearance.
Superman: Brainiac Attacks
Graves appears in this direct-to-video animated film. Her appearance resembles the DCAU version of the character. She is played by Tara Strong.
Graves works for Luthor, who accidentally finds Doomsday while doing illegal digging. He asks her to cover up any connection between Doomsday and LexCorp. When she has done so, he shoots her in the head, to ensure that there are absolutely no links back to him. Her appearance resembles the comics version of the character. She is played by Cree Summer.
A character who shares some similarity with Graves appears in Smallville. She is a combination character, created through an amalgamation of Graves, Eve Teschmacher, and Lena Luthor. Her birth name was Lutessa Lena Luthor, but she is more commonly known in the series as Tess Mercer. She is also referred to by Oliver Queen, with whom she had a romantic fling, as "Mercy". She is selected as the heir to LexCorp by Luthor.
Superman: Shadow of Apokolips
Graves makes an appearance as the bodyguard and chauffeur of Luthor. She is played by Lauren Tom.