Lisa Halle was a villainess on Highlander: The Series two part Season 2 finale, Counterfeit. She was portrayed by Meilani Paul (the then real life wife of Adrian Paul, who plays the series protagonist, Duncan MacLoed) and Alexandra Vandernoot.
She has a history of decieving and using people to her advantage and eventually murdering them. Her last husband who was a psychiatrist tried to understand her, reason with her, only to be murdered for his efforts. She was sentenced to prison for the crime. However, James Horton, a former Watcher turned Hunter had his people break her out of prison. They offered her money, a new face, and freedom in exchange for Duncan MacLeod's death. They altered her to resemble Tessa Noël, Duncan's dead girlfriend. They also made sure she was educated in the art world like Tessa was.
After an attempt to destroy Duncan seemingly failed, Horton launched his final part of his master plan into motion and put Lisa out to meet Duncan. Lisa acted freaked out at first because of the way Duncan approached her, as if she knew her. He would then send her flowers and depsite what his friends Joe Dawson and Richie Ryan's urgings to be careful with her, Duncan would eventually sleep with her. Shortly after Lisa once again pretended to be freaked out by images of Tessa and how much she resembled her, she ran out of his home only to be captured by Horton's people. Of course the kidnapping was staged. Duncan begun to suspect that she was a plant that Horton put out, but Duncan would go to save her anyway.
After Duncan rescued her, she insisted they go to the cemetary to visit Tessa, reminding him she's dead, but Duncan knew that and let her know he was onto her and that after she served her purpose to Horton, he would kill her. After Lisa staged Duncan's death, Horton went to take his head, but then Duncan stopped him. Horton kills Lisa for her betrayal. But he himself was shortly killed after her by Duncan.
After Lisa's death, Duncan gives up his home and he and Richie return to America. Despite all Lisa did to Duncan, she left him with an important gift; the ability to say goodbye to Tessa, the kind of goodbye he could never have given before.