Dr. Wilkerson (Regina Taylor) is a hidden villainess from "Wrong Side of the Road," episode 5.15 of Elementary (airdate March 5, 2017). She is a New Jersey medical examiner who performed an autopsy on Cy Durning, a colleague of Sherlock Holmes.
Durning was murdered by a hitman hired by Eli Kotite, as Durning was one of the people who got Kotite convicted in a hit and run. However, it was later revealed that Wilkerson was paid by the hitman to cover up the murder by falsely ruling it as a natural death, and when encountered by Joan Watson and Kitty Winter, the corrupt villainess boldly stuck to her false claim--despite Joan showing clear evidence against her fallacy.
Wilkerson was later brought into NYPD and interrogated by Joan, Kitty, and Detective Marcus Bell regarding her corruption and collusion with Kotite. During the encounter, the evil Wilkerson arrogantly denied everything, even accusing them of lying about a witness spotting her meeting with the hitman. She later asked if she was under arrest, and when Bell stated that she wasn't (at the moment), Wilkerson left. Later on, Sherlock uncovered evidence of Wilkerson's collusion: $50,000 transferred to her account from one of Kotite's Cayman Islands accounts. It can be assumed that Wilkerson was arrested (off-screen) for her role in covering up Durning's murder.