Laura Lyons is the main villainess from "Hounded," episode 4.16 of Elementary.
She was played by Jennifer Ikeda.
Laura Lyons is an employee at Stapleton Innovations and (as revealed later on) a Baskerville heiress. Her father was Ike Stapleton (who died when Laura was only five), the brother of Laura's boss, Roger Stapleton, whose cousins are Charles and Henry Baskerville. Laura was fourth in line regarding the Baskerville inheritance, and she plotted a murderous scheme to move closer to her goal.
Laura stole GUS 5, one of a collection of 10 robotic dogs created by Stapleton Innovations, and used it to track and stalk Charles Baskerville, which resulted in Charles being struck and killed by a vehicle while attempting to flee. Later on, the evil Laura sent the same machine after Henry, who was on the phone with Sherlock at the time, but Henry successfully escaped thanks to Sherlock's help.
As part of her villainous plan, Laura was going to frame Roger in his cousins' murders, but Henry surviving slightly foiled her scheme. Having figured out that an heir is behind the scheme, Sherlock set a trap to catch the killer, which had Henry "kill" Roger and for the "murder" to be publicized. The "murder" moved Laura to the top of the line, and while collecting, she handed in emails that she claimed were from Roger as part of a conversation they had; they were revealed to be forged by Laura. It was at that moment that Laura heard Sherlock from outside the room, and the villainess was shocked to see Henry and Roger standing behind Sherlock and Joan, as she realized she had been tricked. Laura was later arrested (off-screen) for Charles' murder and the attempt on Henry.