Apasiri Nitibhon, nicknamed Um, is a Thai supermodel and actress. She is the younger sister of Amarin Nitibhon, a Thai singer and actor. She entered the entertainment industry by becoming a model at the age of 18 after the "Trend Setter" contest. Apasiri subsequently appeared in magazines and became known in the modeling industry in the 1990s for her unique looks and her height of 173 centimeters.

She began her acting career at the age of 25, appearing in the film "Sunset at Chao Phraya" in 1995 as Angsumalin. In her youth, Apasiri studied likay dance. In the 2006 film "Victim," she portrayed a beauty queen performing a likay dance. For this role, she had to take a refresher course in Thai classical dance.