Kimberly Hill is the corrupt former police captain of the Star City Police Department.
Following the death of Frank Pike, Kimberly Hill became the new police captain of the Star City Police Department. 24 hours after this promotion, Ricardo Diaz sent an email to her containing surveillance photos of Hill's father, sister, and niece, blackmailing her into working for him.
Sometime later, after James' threat to detonate a thermobaric explosive above Star City, Hill took calls in an attempt to rally everyone together. After Cayden was arrested, Hill allowed Diaz to enter the interrogation room, leading to Cayden's death.
After discovering there were several members of the SCPD working for Diaz, Dinah Drake and Quentin Lance worked together to find out how many police officers were corrupt. During their investigation, Dinah discovers that Hill was one of them.
Oliver eventually confronted both Hill and Armand in his office, revealing that he knew they were working for Diaz. Hill claimed that Diaz threatened her family if she didn't comply. Oliver gave her the opportunity to do the right thing, promising to protect her family. However, Hill arrogantly refused, leaving Oliver no choice but to fire them both. Before cleaning out her desk, Hill fired several police officers who refused to work for Diaz, including Dinah and Nick Anastas.
After Oliver used a device made by Felicity Smoak to copy all of Diaz's files, he gave a list of every individual under his payroll to F.B.I. agent Samanda Watson. Samanda had all of Diaz's allies arrested, including Hill.
Similar to Quentin Lance when he was working with Damien Darhk due to the threats made against his daughter, Laurel Lance, Hill was forced to cooperate with Ricardo Diaz because of this. Hill is proven to prioritize the safety of her family above all else such as when she allowed Diaz to murder Cayden James in her custody, cover up his drug operations, and relieve all the clean cops of their ranks for refusing to become corrupted.
Hill is proven to be quite arrogant; before Oliver Queen had fired her, he gives her the opportunity to do the right thing, and also promised to protect her family, but she refuses to do so, which left him no choice but to fire Hill.
Unlike Quentin, Hill lacks any redeeming qualities; while the former ultimately did the right thing by turning against Damien Darhk, she only kept on disgracing herself. After being fired by Oliver, she held a press conference with Sam Armand to manipulate the public into believing that Oliver fired her and Armand because they were investigating him for being Green Arrow even though Oliver fired them because of their ties to Diaz. This ultimately backfired, after Oliver obtained evidence of Hill's crimes and gave it to Samanda Watson, leading to her getting arrested by the FBI and exposing her crimes to the public.
These negative traits of Hill's, is what eventually led to her deserved/justified incarceration.