Somsiri Sanath Julien Gunatilake (; born 27 October 1955), popularly as Sanath Gunatilake, is a Sri Lankan actor, director, screenwriter and former politician. Known for his versatility across multiple genres, he has had a career in the Sri Lankan film industry spanning over four decades. Gunatilake served as a member of the Western Provincial Council as a member of the United National Party and later held the position of media head for President Chandrika Bandaranaike Kumaratunga.
Gunatilake was born on 27 October 1955 in Mulgampola, Kandy, Sri Lanka, into a middle-class family. His father, Hector Gunatilake, was a lawyer, and his mother, Grace Goonetileke, was a teacher. He has stated that his father was an avid cinema enthusiast, which influenced his early interest in the arts. Gunatilake received his education at Kingswood College, Kandy.
Gunatilake initially worked as a chemistry teacher. He later moved to Colombo in search of new career opportunities, leaving behind his tuition classes in Kandy.
Gunatilake made his film debut in 1978 with Situ Kumariyo, directed by Vijaya Dharmasiri. However, before its release, his second film, Ganga Addara, was screened, followed by Sathweni Dawasa. After Situ Kumariyo, his next film, Vajira, was released.
His breakthrough role came with Ganga Addara, directed by Sumitra Peries, which marked a turning point in his acting career. He later gained widespread recognition for his portrayal of Aravinda in Viragaya, a performance that earned him Best Actor awards at every major film festival in Sri Lanka. Gunatilake has appeared in several notable films, including Kedapatha, Palama Yata, Doorkada Marawa, and Rajya Sevaya Pinisai.
In addition to his more dramatic roles, Gunatilake appeared in several mainstream films alongside Vijaya Kumaratunga, Jeewan Kumaratunga, and Ranjan Ramanayake. His film credits include Koti Waligaya, Dinuma, Raja Wedakarayo, Nommara 17, Obatai Priye Adare, and Inspector Geetha.
In 2009, Gunatilake made his directorial debut with Ekamath Eka Rataka. He was one of the first Sri Lankan directors to actively use the internet for film promotion, launching a website for his film in 2009, onceuponamovie.com.
In 2025 He was married to former actress and businesswoman Janaki Wijerathne. She is the vice president of Lyca Productions.