This is a list of fictional characters in the British psychological crime drama television series Luther, its international remakes and film continuation.

Detective Chief Inspector John Luther, portrayed by Idris Elba, works for the Metropolitan Police Service, in the Serious Crime Unit. He is a legendary figure on the force both for his dedication and his ingenious approaches to solving cases. However, the horrors of Luther's job have given rise to emotional demons which often put him at odds with colleagues and loved ones. Because of this, he constantly breaches protocol and uses unorthodox (and sometimes illegal) methods, such as breaking into properties without warrants to find clues or violently threatening suspects or witnesses. He is also given to belligerent fits of anger. Nevertheless, he is known to hate firearms, and he refuses to kill or directly cause the death of suspects.

Luther studied English at University, where he met future spouse Zoe.

Luther returns from leave to investigate the double murder of Alice Morgan's parents, and quickly realises that she committed the crime. However, Morgan's methodical destruction of evidence keeps Luther from conclusively proving her guilt. A peculiar relationship develops between Luther and Morgan, and Luther approaches her for help on occasion. Morgan insinuates herself into Luther's relationship with Zoe with the intention of helping their marriage, yet her means only further complicate Luther's personal problems.

When Zoe is shot and killed by Luther's best friend, the corrupt Detective Chief Inspector Ian Reed, Luther – known for his violent temper – is blamed for the murder because Reed sets up the crime scene to implicate him. Luther subsequently becomes the focus of a citywide manhunt. Events transpire during which Alice kills Reed during a confrontation between him, on one side, and her, Luther, and Zoe's boyfriend Mark on the other, at a deserted Waterloo station. After providing proof that Reed murdered Zoe, Luther is allowed to return to the service, where he has now been assigned to the reorganised Serious and Serial Crime Unit, headed by DSU Schenck.

At the start of the second series, Luther has moved into an unmaintained flat at the Aylesbury Estate and shows suicidal tendencies. Luther also desires to leave the Met. He is approached by Caroline Jones, the wife of one of his former suspects, who asks him to locate her delinquent daughter, Jenny. When Luther tracks down Jenny and rescues her from a pornography shoot, the production's backers, Toby Kent and his grandmother, "Baba", violently pressure the inspector to hand her back. Rather than doing so, Luther strikes an illegal deal to provide them with information, in exchange for setting Jenny free. When Jenny kills Toby in self-defence, Luther manages to cover up her crime and threatens Baba with a visit from Alice if she continues to harass Jenny and her mother.

Idris Elba said of his character, "You know when you watch the news and someone has killed their children? And your instinct is to be like, 'Oh, if I got my hands on them'? Well, his instinct is to do that but he's a police officer. And when he does get his hands on them, he doesn't necessarily follow procedure. He will be as vindictive as the criminal".

Alice Morgan, played by Ruth Wilson, is a research scientist with a genius-level IQ. When first introduced, Alice has murdered her parents – and their dog – in such a calculated fashion, that not even Luther is able to prove her guilt, of which he is absolutely certain. Alice's core belief, that nothing in life ultimately matters, comes into direct conflict with Luther's own beliefs. She frequently insinuates herself into Luther's professional and personal life, both as an enemy and ally, with behaviours ranging from stalking him and those close to him, to helping him avoid criminal prosecution. She also provides Luther with a unique insight into the criminal mind. Luther describes Alice as a malignant narcissist.