Hedwig Tam Sin-yin (Chinese: 談善言; born 29 March 1990) is a Hong Kong actress. She received a nomination for Best New Performer in the 36th Hong Kong Film Awards for her debut role in Weeds on Fire (2016), and gained recognition for her breakout role as Chong Wai in the ViuTV series Warriors Within [zh] (2020–2024).

Tam also starred in the films The First Girl I Loved (2021), Hong Kong Family [zh] (2022), and Smashing Frank (2025). In 2025, she won Best Actress in the 31st Hong Kong Film Critics Society Awards for her performance in Montages of a Modern Motherhood (2024).

Tam was born on 29 March 1990 to a middle-class family. Her Chinese given name Sin-yin (善言) was chosen by her parents and means "kind words". She chose her English given name Hedwig for its meanings of "combat and persistence". She grew up in Ma On Shan as a middle child with an older sister and a younger brother. Her father worked as an expatriate outside Hong Kong. Tam described herself as not enjoying studying during her school years, and instead being passionate about sports, having participated in volleyball and basketball since primary school. She studied at Po Leung Kuk Wu Chung College [zh] for secondary education, where she was classmates with fellow actor and singer Stanley Yau. During her university years, she assisted a friend in organizing a fashion show, where she met industry professionals and inadvertently entered the field, working part-time as a costume dresser for models. After graduating with a bachelor's degree in marketing and public relations, she was invited to model due to her company's expansion and began her modeling career in 2012, primarily filming television advertisements. That same year, she also started acting in short films, describing her motivation to pursue acting as a "desire for fun and new experiences". She moved out of her family's home in Ma On Shan after entering showbiz and has lived in Tai Po, Tai Wai, and Yau Tsim Mong over the years.

Tam made a brief appearance in the 2012 RTHK anthology series DIY2K [zh], before landing her inaugural role as Tsz-ching, an unwed pregnant teenage girl, in the 2016 film Weeds on Fire. Tam auditioned for the role based on a friend's recommendation, initially believing it was for a short film for the Fresh Wave International Short Film Festival [zh]. She described Weeds on Fire as a turning point in her life, as it inspired her desire to become an actress and garnered her the public attention needed to land future roles. She was nominated for Best New Performer in the 36th Hong Kong Film Awards, although she lost to her co-star Tony Wu. She also played the daughter of Alan Tam's character in the triad film Fooling Around Jiang Hu in the same year.

In 2017, Tam starred as Sam, the lesbian best friend of Larine Tang's character who is secretly in love with her, in the comedy film The Yuppie Fantasia 3. To prepare for her role, Tam drew inspiration from films like All About Love (2010), Blue Is the Warmest Colour (2013) and Carol (2015), and based her character on a lesbian friend. She also received a minor role in the drama film Tomorrow Is Another Day that year.

In 2018, Tam played one of the best friends of the female lead Kathy Yuen in When Sun Meets Moon [zh], followed by a lead role as Ka-shun, a bride-to-be who is diagnosed with a brain tumor, in Adieu [yue]. She then landed a main role in the ViuTV sci-fi romance series If Love Was Not Timeless [zh], alongside her Weeds on Fire co-star Lam Yiu-sing, where they played a couple. She also had minor roles as Bi, the daughter of an infamous robber (played by Philip Keung) in the Shaw Brothers drama series Guardian Angel, and as Lo Tin-yi, a second-generation rich teenager who gets kidnapped in the Fox Networks crime thriller series Stained [zh].

In 2019, Tam took on another main role in a ViuTV romance series Till Death Do Us Part [zh], playing a mistress who intervenes in the marriage of leads Sheren Tang and Sunny Chan, as well as the pole dancer Moon in the drama film The Lady Improper [zh]. She also made a cameo appearance as a university hall cheerleader in Neo Yau's ViuTV drama series Haters Gonna Stay [zh], alongside Stephy Tang, Angela Yuen, Jennifer Yu, and Yanny Chan.

In 2020, Tam received her breakout role in the ViuTV sports series Warriors Within [zh] as Chong Wai, a karateka aspiring to represent Hong Kong at the Olympics. Tam was initially hesitant to accept the role when approached by producer and lead actor Stephen Au, as she had no martial arts background. To prepare, she underwent three months of karate training before filming. The series broke viewership records for ViuTV in its first week. Calvin Choi, writing for am730, commended Tam's portrayal of Chong as "authentic", noting her ability to carry the production; Chan Pak-yu of HK01 highlighted her as the series' standout, commending her dedication to preparing for the role and her powerful fight scenes, while also delivering convincing emotional performances. Tam made a guest appearance as the younger version of Catherine Chau's character in the ViuTV-Youku drama The Gutter [zh] that year. Ngai Ga of Harper's Bazaar commended Tam's acting as "quite capable", while Choi at am730 noted that she was the reason he watched the series, particularly praising her performance in a one-take monologue. HK01 also reported on the acclaim Tam received on social media for her one-take scene. She later appeared in the music video for Eason Chan's 2020 single "Love Perhaps [zh]", and the LARP-themed variety program All Suspicious [zh] as a cast member.