Siam Ahmed (born 29 March 1990) is a Bangladeshi film actor. Known for his versatile roles, style, and intensity, he has often portrayed flawed heroes on screen. He made his debut in the Bangladeshi telefilm Bhalobasha 101 and is best known for his TV series Nine and a half and debut role in the film Poramon 2 (2018) directed by Raihan Rafi. He is also well known for his various roles in Bengali TV dramas. He won the Bangladesh National Film Award for Best Actor twice for his roles in Bishwoshundori (2020) and Mridha Bonam Mridha (2021).

Siam was born in Dhaka on 29 March 1990. He completed his Secondary School Certificate (SSC) from Motijheel Model School and College, and later graduated from Notre Dame College, Dhaka with a Higher Secondary Certificate (HSC). After completing HSC, he studied Accounting and Information Systems (AIS) at the University of Dhaka. Later, he completed his Diploma and LLB Hons from University of London. He did his Bar Professional Training Course (BPTC) from Lincoln's Inn. He also did his PGDL from Northumbria University Newcastle.

Siam Ahmed started his career as a model for Airtel Bangladesh. His first drama was Bhalobasha 101 by Redoan Rony. After that he acted, one by one, in many TV dramas including Megh Enechi Bheja, Happy Ending, X factor Reload, Tomar Amar Prem etc. He has been praised a lot for his short film Bokhate. In 2018 he joined Dhallywood and his debut movie was PoraMon 2. He also performed in some music videos like Bondhurey, Cholna Sujon, Tumi Chaile, Deyale Deyale etc. He also worked in Hoichoi web film Lilith starring Masuma Rahman Nabila.

Siam Ahmed is married to Shamma Rushafy Abantee since December 2018.