Alex Cross, the main character of the series. Born Alexander Isaiah Cross, he has a Ph.D. in Psychology from Johns Hopkins University and has worked for both the Washington, D.C. Police Department and Federal Bureau of Investigation. His mother died of cancer and he thought his father was dead as well. His wife was murdered by an assassin, which leaves Cross a widower with two children and his grandmother, Nana Mama. In the first few books he is alone until he meets and falls in love with a woman named Christine, with whom he has a third child — a boy — named Alex Jr or Ali. During the books Cross is hunted by a criminal/threat in Washington, D.C., where he lives, which causes Christine to leave him out of fear. He is a detective who tries to be as close to his family as can be. After Christine left him, Alex later started dating again, but some of the women have either died or left him over the course of the novels. By the novel Cross, Alex discovers that an assassin named Jimmy Hats Galati, murdered his wife and was killed by his best friend, John Sampson, who didn't want Alex to go down the road of revenge. Now having solved the murder of his wife, Alex finds the will to move on with his life, finding peace for the first time. In the newest books, he begins a relationship with Bree Stone, whom he eventually marries. Since Roses Are Red up to Cross Fire, The Mastermind, Kyle Craig, has been his primary enemy. It is unknown exactly why Craig wants to kill Alex however. Craig is to have supposedly died in Cross Fire. Cross allows the adopted girl, Ava (after Nana Mama finds her in Kill Alex Cross), to live with his family. Alex marries Bree in Cross Fire and is finally at peace with her. He has had three major love interests throughout the series, Maria Cross (his deceased wife), Christine Johnson (his ex-girlfriend, whom he'd been engaged to), and Bree (his current wife). He has been friends with Sampson since he was 10, meaning they've been friends since he first arrived in Washington, D.C. In Alex Cross, Run, Alex faces several cases and his life becomes severely complicated. When Ava is murdered, he finds her killer and avenges her death along with Bree. However, he still faces several issues: problems with his new wife, Bree; what he will do after Ava's death and whether he will continue being a detective; if he may have children with Bree; and if he will ever stop having to face the recurring problem in his life - endangering himself and his family all the time. Finally, his shrink says she will help him deal with his life for as long as it takes.
John Sampson, is Cross's best friend since childhood and also his partner. Sampson, in Cross is known to have killed Jimmy Hats Galati, Alex's deceased wife's killer. John explains that he didn't want to see Jimmy get away with murdering Alex's wife and also didn't want to see Alex go down a road of revenge and had decided to avenge Alex's wife for him. In another book, Double Cross he is taken hostage while trying to solve the case with Cross's new love interest, Brianna Stone. In earlier books, the first few, he is seen to have had been in love with Nina Childs, who dies in Pop Goes the Weasel causing him to vow to find the killer and get him. In Along Came a Spider some background history is told, one being that when Alex moved to Washington, D.C., after his parents' death (and his move with grandmother Nana Mama) he instantly became friends with Alex. They were known for robbing grocery stores when they were teenagers. Sampson got married in Four Blind Mice to a woman, who he fell in love with, named Billie, despite his reluctance since he is afraid of being a father because his parents were so horrible. It is said that Billie is first and only girl that he has ever had sex with. In , Run Sampson informs Alex that Ava has been killed and later assists Bree and Alex in avenging Ava's death.