Nancy Sit Ka Yin (Chinese: 薛家燕) is a Hong Kong actress on the TVB network. Her acting career dated back to the 1960s, when she was a popular teen idol alongside Connie Chan Po-chu, and Josephine Siao. Sit recorded many albums in her teens, and later served as a mentor to Anita Mui, who went on to become one of the biggest superstars in Hong Kong history.

She first starred in the long-running series A Kindred Spirit, playing one of the show's central figures. It was the longest-running series in Hong Kong history, with more than 1,000 episodes.

In 2000, Nancy is the first actress to be awarded the HKSAR Medal of Honour in Hong Kong. Nancy is the first actress to be awarded "Outstanding Women Professionals Award" at "The Outstanding Women Professional and Entrepreneurs Awards 2014" organized by Hong Kong Women Professional and Entrepreneurs Association. The TVB variety show Walk The Walk, Talk The Talk she hosted with Wong Cho Lam is also awarded "My Favourite TVB Variety / Infotainment Programme" and "My Favourite TVB Variety Show Host" at Star Hurb Awards 2014 in Singapore.