Will Simpson is a protagonist-turned-antagonist of season 1 of the web television series Jessica Jones. He is a police officer from the New York City Police Department who became obsessed with tracking down and killing Kilgrave after an encounter with him. Initially appearing as an ally to Jessica Jones and Trish Walker, he slowly goes off the deep end when he begins to disagree with Jessica's methods and gets consumed by obsession and paranoia, eventually turning against Jessica when he suspects that she's actually helping Kilgrave.
He is portrayed by Wil Traval.
Simpson was presumably a good cop in the past. He had enough reason and common sense to stop usingCombat Enhancers as it made his rage uncontrollable. However after being "Kilgraved" and attempting to killTrish Walker, then later to commit suicide he became reckless and obsessed.
Eventually killing Kilgrave became his only goal. He was willing to help Jessica Jones (another victim of the latter) murder the man however he didn't agree with her letting him live as to clear the name of Hope Shlottmanand wasn't all that concerned if it may have cost the lives of the few in the process. Despite this Simpson felt undeniable guilt for his forced actions of trying to kill Walker and eventually the two became lovers. Even under the uncontrollable influence of Combat Enhancers, he still gave Trish the chance to walk away as he didn't want to hurt her.
However after a failed attempt on Kilgrave's life which resulted in the death of two of his soldiers and him being severely injured Simpson had no choice but to return to the Combat Enhancers which cured his body but had a traumatic affect on his psyche. On the Enhancers affect Simpons was violent, crazed and homicidal. His devotion to murdering Kilgrave went to a degree of almost ruthlessness. Simpson had no concern over breaking the law, murder was no inconvenience to him as he did with Oscar Clemons when he planned to lock Kilgrave away instead of killing him.
Evidently the rage of the Combat Enhancers mixed with his need for revenge against the mind controller was all aimed towards Jessica as Simpson thought that she was too emotionally involved in trying to bring down Kilgrave and acted extremely aggressive toward her, to the point of violently attacking Jones in her apartment.