Vengeful villainess Lena Gilborne (aka Leanne Randall)
Lena Gilborne aka Leanne Randall (Sara Vickers) is the hidden villainess of Season 3 of BBC's Shetland. She was a woman who became involved in the case of Robbie Morton, a man she met on a ferry boat who later went missing and was ultimately found dead in a shipping container. Throughout the case, Leanne appeared deeply traumatized by Robbie's death, and began following Michael Maguire after learning he was the top suspect in the case. Her vigilantism eventually led to Leanne being shot as a hitman attacked Michael and ultimately shot him to death.
Michael's death eventually led to the reveal that his real name was Michael Thompson and was in Witness Protection to testify against gangster Arthur McCall. This also led to a revelation regarding Leanne: her real name was Lena Gilborne, and she had previously been in the Witness Protection program along with her mother Anne after Anne witnessed a crime while on holiday, with her handler being Asha Israni. Anne ultimately gave her testimony despite receiving threats, only for the case to fall through on a technicality, with Asha relocated Anne and Lena from Shetland to the mainland. Anne was unable to cope with the transition and subsequently committed suicide, leaving Lena heartbroken and vengeful against Asha, believing her mother's death was Asha's fault.
Years later, Lena (having adopted the name Leanne Randall) spotted Asha at the Lighthouse Hotel with Michael, leading her to begin stalking Michael in a ploy to eventually get to Asha. After seeing Robbie get into an argument with Michael, Lena attempted to convince Robbie to help her in her revenge plot by reporting Michael to the police. When Robbie refused, Lena went with Robbie after he became drunk to the shipping containers and went with him inside one, with the villainess locking him inside the container after he passed out. Robbie eventually suffocated to death inside the container, with Michael being believed to be behind his death. In the wake of Robbie's death, the evil Lena also sent an email to Calvin Sarwar (Arthur McCall's lawyer) revealing Michael's location, leading Calvin to have Michael killed.
The final episode of the season had Lena confronting Asha directly at her hotel room, revealing her identity and becoming irate at Asha for not remembering her and her mother. Asha attempted to express sympathy for Lena before going to take a phone call (the call being from DI Jimmy Perez to warn her about Lena), with the enraged Lena warning not to answer the phone before stabbing Asha with a kitchen knife. Jimmy and DS Alison "Tosh" McIntosh eventually located Lena after she fled the hotel, with Lena confessing to attacking Asha as well as killing Robbie and setting up Michael's death, accusing Asha of abandoning her and her mother and revealing that she had expected the police to rescue Robbie before he died. Asha was ultimately rescued and survived her injuries while Lena was placed under arrest. Her final scene had Lena being handcuffed as she was escorted to be transported to the mainland, with the villainess correcting the guard by telling him that her name was Lena, not Leanne.