Grace Larsen is the main villainess from "Autopsy Turvy," episode 6.14 of Psych.
She was played by the late Glenne Headly.
Grace's backstory reveals that she is a former classmate and lover of SBPD coroner Woody Strode back in college. They ended up taking different paths after graduation, with Woody becoming a coroner while Grace ended up working as a mortician. Grace became insanely jealous of Woody's success and devised a fiendish plot to steal his job. Her plan included killing a man named Bob White and severing his ear to make it appear that Woody botched the autopsy.
Grace's plan works, and she ends up working side by side with Woody, which led to the two of them rekindling their past romance. Unbeknownst to Woody, a man named Whip Chatterly was on to what Grace was really doing, and she ended up killing him to keep her secret. She set up Whip's murder to look like a suicide, and even wrote a note pinning Whip as Bob's killer. Shawn and Gus' attempt to call Woody about Grace was thwarted by the villainess, who later pointed a gun at Woody after she was found out. Grace revealed her jealousy of Woody and his success, and had intent on killing him before Juliet entered and arrested Grace.