Stefanie Martini (born 6 October 1990) is an English actress, known for her leading role in ITV's 2017 production Prime Suspect 1973. She also starred in Doctor Thorne (2016), Emerald City (2017), the 2017 film Crooked House and the TV series The Last Kingdom.

Born in Bristol, Martini was raised in villages in North Somerset by her parents.^[2] She completed her secondary education locally.^[3] Having starred in local youth plays with Winscombe Youth Theatre and undertaken the two week induction at the National Youth Theatre,^[2] with an interest in illustration post A Levels at Churchill Academy and Sixth Form,^[4][5] she began an arts foundation course. However, a teacher suggested that if she was interested in acting, then she should try it.

After failing to get into RADA on her first attempt, Martini joined a one-year programme at the Bristol Old Vic Theatre School, where the company wrote their own plays that they produced in local schools.^[2][6] She was subsequently accepted into RADA the following year.^[2]

During Martini's third year at RADA, she played the supporting role of a suspect in an episode of the TV series Endeavour.^[6] In 2016, she starred as Mary Thorne in Doctor Thorne,^[7] and Princess Langwidere in NBC's Emerald City. Martini portrayed the lead role of Jane Tennison in ITV's 2017 production Prime Suspect 1973, a prequel to the TV series Prime Suspect which had starred Helen Mirren.^[8] She also played Sophia de Haviland in the 2017 film Crooked House, an adaptation of the Agatha Christie novel of the same name.^[9]

From 2020 to 2022, Martini portrayed Eadith in the Netflix series The Last Kingdom for seasons four and five.^[10] She will star in the World War II science fiction drama Lola, scheduled to be released in early August 2023.^[11]

On 26 June 2021, Martini came out as bisexual in an Instagram post.^[12] Since late 2021, Martini has been in a relationship with English Intimacy Coordinator/model El Wood, which she announced publicly on social media on 1 January 2022.^[13]