Mary Elizabeth Chieffo (born November 7, 1992) is an American actress known for portraying the Klingon L'Rell on the television series Star Trek: Discovery.^[1]

Chieffo was born on November 7, 1992,^[2] in Los Angeles, California.^[3] She grew up in the neighborhood of Valley Village, Los Angeles in California, only daughter of actors Michael Chieffo and Beth Grant.^[3]

She attended the Drama division of Juilliard School in New York City, earning a Bachelor of Fine Arts degree in 2015.^[4] One of her classmates was future Star Trek: Discovery castmate Mary Wiseman.^[5]

Chieffo came out publicly as a lesbian on the red carpet prior to the Star Trek Day event held September 8, 2021, at the Skirball Cultural Center in Los Angeles, California.^[6] She later clarified that she identifies as "panromantic demisexual and proudly in a lesbian relationship".^[7] A few days later, she confirmed via her Twitter feed that she was dating writer and actor Madi Goff.^[8] Chieffo wrote the introduction essay for the 2023 edition of Marvel's Voices: Pride #1,^[9] reflecting on the need for queer representation in media.^[10]

Her first high profile acting position was on Star Trek: Discovery, where she played the recurring character of L'Rell, a Klingon warrior and spy who becomes leader of the Klingon Empire at the end of Season 1.^[11] Her writing and producing debut was Operation Othello, a virtual reality adaptation of Shakespeare's Othello, where she also plays Lt. Iago in a gender twist from the original play.^[12] In 2022 she reprised her role as Iago in "Iago: The Green Eyed Monster", a 6-minute futuristic musical AR prequel to Othello, nominated for "Best Immersive Experience" in the 2022 Tribeca Festival.^[13]