Lydia Mackay is an American voice and stage actress recognized for her extensive work in English dubs of anime series and films, primarily produced by Funimation and OkraTron 5000. She is also an associate professor of theatre and continues to perform on stage.

Mackay's career in voice acting began in 1998 when she auditioned for Funimation's production of Dragon Ball Z, landing her first role as Cynthia. With a foundation in live theatre, she holds a Bachelor of Fine Arts in Theatre Arts and a Master of Fine Arts in Acting. Her approach to voice acting is grounded in her stage experience, emphasizing that vocal performance requires full physical and emotional engagement.

Over a career spanning more than two decades, Mackay has voiced over 150 characters across anime, video games, and animated projects. She is represented by the Mary Collins Agency of Dallas and is a member of the Actors' Equity Association.

Mackay has portrayed a wide range of characters in major anime series. She is well-known for her role as the Pirate Empress Boa Hancock in the long-running series One Piece, a part she has also played in several films and specials, including One Piece: Stampede and One Piece 3D2Y: Overcoming Ace's Death! Luffy's Pledge to His Friends. Another significant early role was providing the voices for Trisha Elric and the homunculus Sloth in the 2004 series Fullmetal Alchemist, later returning as Trisha for Fullmetal Alchemist: Brotherhood.

Her filmography includes prominent roles in numerous other popular titles. She voices Shion Karanomori in the Psycho-Pass franchise, a role she has played across the television series and multiple films, including Psycho-Pass: The Movie and Psycho-Pass Providence. In the A Certain Magical Index and A Certain Scientific Railgun series, she is the voice of the powerful esper Shizuri Mugino. She also appears as Kyoko Honda in Fruits Basket and Fruits Basket: Prelude, as well as Nanaba in Attack on Titan.

Mackay's other notable voice credits encompass a diverse array of characters. These include Madam Red in Black Butler, Ultear in Fairy Tail, Tokiko Narukami in The Day I Became a God, Tsukiumi in Sekirei, Slice in My Hero Academia: Heroes Rising, and Vanessa Enoteca in Black Clover. In video games, she is known for her roles as Athena in the Borderlands series and Ambra in Battleborn.

Beyond her work in the recording studio, Lydia Mackay is dedicated to theatre education, serving as an Associate Professor of Theatre at Texas Christian University. She remains an active presence at fan conventions, where she meets audiences and participates in industry events such as the New York Comic Con.