The evil Deborah Boyd
Deborah Boyd (Mary Beth Peil) is a villainess from "Alien", episode 7.11 of Law & Order: SVU (airdate December 6, 2005). She is the mother of Kate Boyd and the maternal grandmother of eight-year-old Emma Boyd.
Deborah was first shown visiting her daughter in the hospital (as Kate was dying from lupus), while lashing out at Kate's girlfriend Zoe Dunlop as well. In the episode, Emma was revealed to have stabbed 12-year-old Sean Hamill with a pair of scissors, due to Sean's homophobic bullying towards Emma, and once Emma was ordered to counseling and set to be released in Zoe's custody, Deborah and her husband, Oliver Boyd, filed for custody of their granddaughter.
The progression established Deborah as a homophobic villainess, as she voiced her opposition to Kate's relationship with Zoe and believed the latter coerced her daughter into "turning" gay, and it was later in the episode that Deborah manipulated Emma into portraying Zoe as an evil child molester--with Emma making claims that Zoe continuously raped her. Photos of Zoe and Emma in their bathtub together appeared to be damning towards the former, only for Zoe to state that she and Kate (who passed on during the episode) the photos were taken to build up Emma's confidence. Dr. George Huang was able to pinpoint that Emma wasn't truthful in the claims, as Emma's description was analytical, not emotional, while also deducing that Emma was coached by Deborah.
Both Deborah and Oliver were arrested, and as they took the stand, the evil Deborah continued her homophobic stance by revealing she felt gay couples shouldn't be allowed to raise children and stating that she found studies that showed that children raised by LGBT couples would most likely be sexually abused and grow up sexually confused and promiscuous. The villainess also revealed that she was given this information by James Decker (Deborah and Oliver's attorney), which led to the conclusion that Decker used them for his own homophobic agenda.
Even after Casey Novak revealed to Deborah that the studies she found were fraudulent, Deborah continued to defend the statements and claim that she was motivated by a desire to protect Emma. Her pleas for forgiveness were met with anger from Zoe, who lashed out at the villainess for manipulating Emma into believing that Zoe raped her, adding that she would never trust Deborah again. It was mentioned in the final scenes that Deborah and Oliver would testify against Decker, most likely accepting a plea deal to do so.