- "If there's a killer out there, I'm gonna stop him, especially if he's a threat to someone I care about."
- —Billy Malone[src]
Detective William "Billy" Malone (died December 7, 2016) was a police detective of the Star City Police Department, a member of Mayor Oliver Queen's Anti-Crime Unit, and the boyfriend of Felicity Smoak. He investigated the case of the "Throwing Star Killer", before eventually getting abducted by Prometheus and set up as bait for Green Arrow.
Around September 2016, Billy began dating Felicity Smoak. Billy, along with Frank Pike, was investigating the murder of a policeman by a certain criminal. When the man showed the captain the scene of the crime, he stated that the style of leaving the coins in front of the victim's eyes suited Charon - a dangerous criminal who had set himself up in Star City after serving in Hub City and Blüdhaven. The conversation, however, quickly turned to the subject of Quentin Lance, when he mentioned to Benton that the captain might bring him back into service. Late in the evening, when Felicity returned to her apartment, Billy approached her and hugged her, asking how her day was 
When Ragman attacked a medical event sponsored by AmerTek Industries, Rene Ramirez was able to grab a piece of cloth from his suit, which he gave to Felicity in the hope that the Green Arrow could use this evidence to track down the rogue vigilante. Felicity, in turn, asked Billy to process the piece of cloth in the Star City Police Department's gas chromatograph, under the guise that the rag belonged to a friend's cleaning woman who had gone missing. Billy asked if she wanted to file a report for a missing person, but Felicity declined. Though Billy could tell she was not being entirely truthful due to how Felicity kept changing her story, he agreed to help her anyway and remarked that he had not yet met any of her friends before emphasizing that this was a hint that he would like to meet them.
Billy triggered a false alarm, triggered by the Green Arrow. He did it because he had something to say to him, and he had no other way of contacting him. He wanted to tell him that someone smarter and more dangerous is hunting him and that he murdered Conahan and also attacked Tobias Church.
During the break from work, Billy went to Felicity at her request, where they spent an hour together. The boy told the girl that he had signed up with ACU and wanted to know if the Mayor Queen knew about the new IT boyfriend. Some time later, Billy met Oliver, unaware it was actually Human Target, and spoke to the man about Miss Smoak's relationship.
After a hard day, Lopez presented Billy with evidence in the murder of Gay Eked. The man was not pleased with the fact that they did not have a way to catch the criminal after all. When Felicity suddenly visited him and she started acting rather strange during a conversation that didn't end due to Pike's summons. Sometime later, Felicity visited the boy again, asking him for a private and frank conversation during which she confessed that she had stolen the evidence from his desk that was needed for her cooperation with Green Arrow. Billy quickly turned his anger into delight and pride in a woman, then began to ask questions. The IT specialist, knowing that she could not reveal it, interrupted the conversation with a passionate kiss.
Billy eventually succeeded in finding out the identity of Mr. Terrific, which he revealed to Felicity, but not to Paul Holt. Despite Felicity's pleas, he investigated Prometheus's attack on Curtis Holt, discovering the connection between the Dycloseral drug in Curtis's blood and Claybourne Pharmaceuticals. Arriving at Claybourne Pharm abandoned manufacturing plant, he investigated the CEO's office, finding a picture of a baby. He made a photo of the picture with his phone, sending it to Felicity. As he turned to leave the premises, Prometheus ambushed Billy and abducted him. As the Green Arrow hunted down Prometheus to the site of his old confrontation with Justin Claybourne at an AK Desmond Group hideout, Billy was forced to wear a copy of Prometheus's suit, with a radio speaker from the real Prometheus adjusted to his armor. As Green Arrow pursued the villainous vigilante into a hall of mirrors, the real Prometheus escaped, leaving Billy behind as a target for Oliver. With everything going according to Prometheus's plan, Oliver shot and killed Billy as soon as he saw him, mistaking him for Prometheus, only to discover his error shortly after. The scene ends Prometheus saying Green Arrow that every person close to him dies.
Billy's death was avenged when Prometheus killed himself on May 17, 2017, upon the failure of his plans.
- High-level intellect/Expert detective: As a detective of the SCPD and a member of the ACU, Billy was a capable detective, being as successful as Team Arrow in finding info on Justin Claybourne's connection to Prometheus.
Behind the scenes
- In DC Comics the surname "Malone" is most well known as the identity of a posthumous criminal that was stolen by Bruce Wayne/Batman and used for his own investigation missions in the criminal underworld. His first name is "Matches", and his primary role is that of a false identity for Batman to take on, allowing the Dark Knight with a useful 'in' to the criminal underworld without needing to establish an original identity with a fake reputation.