Ghantasala Sai Srinivas Sivakumar (born on 16 November 1983), professionally credited as Thaman S, is an Indian composer and playback singer known for his works majorly in Telugu and Tamil cinema. He is the recipient of the National Film Award for Best Music Direction for his work in the 2020 musical hit Ala Vaikuntapuramulo.

His breakout film as a music director was Kick (2009). His notable compositions include films such as Eeram (2009), Brindavanam (2010), Mirapakay (2011), Osthe (2011), Dookudu (2011), Businessman (2012), Naayak (2013), Baadshah (2013), Greeku Veerudu (2013), Ramayya Vasthavayya (2013), Race Gurram (2014), Aagadu (2014), Bruce Lee (2015), Sarrainodu (2016), Tholi Prema (2018), Aravinda Sametha Veera Raghava (2018), Ala Vaikunthapurramuloo (2020), Krack (2021), Vakeel Saab (2021), Akhanda (2021), Bheemla Nayak (2022), Varisu (2023), Bhagavanth Kesari (2023) and Guntur Kaaram (2024).

Thaman has been the judge in the reality singing show Telugu Indian Idol. He is known for his frequent collaborations with Ravi Teja, Surender Reddy, Sreenu Vaitla, Trivikram Srinivas, and Boyapati Srinu.