She was played by Penny Fuller.
Joyce Pollock is the wife of Dennis Pollock (aka Dennis Beck), having married Dennis at some point prior to the episode's events, but as it turned out, the marriage was arranged by Dennis' mother, Liann Crosby, as part of their original plan to kill Joyce. However, as time progressed, Dennis developed true affections for Joyce, leading to Liann (who sensed Dennis' love for his wife) planning to kill Joyce by sabotaging her gas heater. Joyce survived and during her first encounter with detectives Rey Curtis and Lennie Briscoe regarding Dennis' whereabouts, the pair was led to believe that Dennis was Joyce's son, only for Joyce to reveal that they were husband and wife.
Dennis ended up arrested for killing Stuart Wattman during an earlier attempt to kill Liann, and Joyce was shown sitting with her husband as he faced an additional charge of a second attempt on Liann, as a package with a gun inside was sent to Saratoga Springs, where Liann was at the time. Joyce continued to stand by Dennis, adding that she wouldn't let Dennis spend time in prison, while voicing her affections for her husband and stating that he felt the same. Following the revelation of Liann and Dennis' familial ties, as well as the former's various villainous activities, Jack McCoy offered Dennis a plea deal to testify against his mother, which also included the reveal that a warrant was out for Joyce's arrest for conspiracy to commit murder.
As McCoy and Abbie Carmichael both revealed, Joyce turned heel by planning to kill Liann herself, and she was the one who sent the package with the gun inside as part of her plan to head to Saratoga Springs and kill Liann. The villainess' plan was made under her knowledge that Liann and Dennis were connected, but she was unaware of their true ties to each other, and as Dennis thought about it, the evil Joyce pleaded with her husband to take the deal, adding that her actions were for her and Dennis. Despite everything that Liann put him through, and the fact that the deal would completely exonerate Joyce, Dennis turned it down and refused to testify, much to the extreme shock of Joyce. As a result, Liann avoided all punishment, and Joyce was arrested (off-screen), with McCoy stating that Joyce was facing 8 1/3 years in prison.