Dr. Jill Tuck, played by Betsy Russell, is a character who appears throughout the Saw film series.
Jill Tuck, the ex-wife of John Kramer, appears briefly in Saw III as part of a memory that John recalls while he is undergoing brain surgery. She is interrogated by FBI Agents Peter Strahm and Lindsey Perez in Saw IV, revealing Jigsaw's backstory. In Saw V, after John's death, Jill visits his lawyer to hear his will, during which she is bequeathed a box containing his last intended test subjects, including one test that Jill must carry out herself. Submitting to his final wishes, Jill placed Mark Hoffman in a seemingly inescapable trap, intending to kill him.
After Hoffman escapes the trap, Jill flees to his precinct station and asks for help from Detective Matt Gibson in Internal Affairs, offering to incriminate Hoffman in exchange for immunity and protection. While Jill is in protective custody, Hoffman infiltrates the station and kills her with the reverse bear trap. Her death is subsequently avenged by Dr. Lawrence Gordon, who was instructed in a tape left for him by John to watch over Jill and to act immediately on John's behalf if anything happened to her.
She is briefly mentioned in Jigsaw, when it is revealed that the main game is taking place at a pig farm that had been owned by her family, until it had to close due to an outbreak of Aujeszky's disease.