Claire Whitfield is a one-shot villainess from Diagnosis Murder, appearing in Season 4's "The Merry Widow Murder".
She was portrayed by Brynn Thayer.
Claire Whitfield is the scheming wife of the wealthy Elliott Whitfield, but as shown in the beginning with the episode, she was having an affair with a younger man, Max Halleck. Claire planned to kill Elliott and inherit his wealth, and her evil plan started with Max punching Claire to make it look like Elliott was abusive towards her. She later went up to Mark Sloan and informed him of the bruise and her worries that Elliott has sleep apnea. To make sure that the claims are passed off as fact, Claire records Max making snoring noises, and gives the tape to Mark while claiming that the snores belong to Elliott.
Claire later checks in to a hotel room, but this was part of the centerpiece of her plan to kill her husband. She later drove back home and committed the act by drugging Elliott's warm milk, then later bringing out Max to place Elliott on his bed, where he was smothered with a pillow. It was made to look like Elliott died of sleep apnea, and after the deed was done, Claire and Max drove to their hotel room together. Both Mark and Steve Sloan were on the case, but Claire attempted to take care of that when she released a video of herself acting seductive with Mark, making it look like they're having an affair. Claire's ruse is revealed when she's interrogated by Steve, and it is there that she sold out Max, claiming that he killed Elliott on his own. Unbeknownst to Claire, Max was outside the interrogation room hearing Claire sell him out, and he angrily enters and implicates Claire's role in the murder. Both Claire and Max were arrested.
- Brynn Thayer played a villainess in both of her appearances on Diagnosis Murder, later appearing in Season 7's "Man Overboard" as the evil Clare Brantigan.