Filemon Lagman
| "Ka Popoy"  Lagman | |
|---|---|
| Personal details | |
| Born | Filemon Castelar Lagman March 17, 1953 Bicol, Philippines | 
| Died | February 6, 2001 (aged 47) Quezon City, Philippines | 
| Manner of death | Assassination by gunshots | 
| Political party | Partido ng Manggagawang Pilipino (1999–2001) Sanlakas (1993–2001) Communist Party of the Philippines (until 1991) | 
| Relations | Edcel Lagman (brother) | 
| Occupation | Marxist theoretician, Labor Group Leader | 
| Known for | Founder of Bukluran ng Manggagawang Pilipino (BMP), Kapatiran ng mga Pangulo ng Unyon sa Pilipinas (KPUP) | 
Filemon Castelar Lagman (March 17, 1953 – February 6, 2001), popularly known as Ka Popoy, was a revolutionary socialist and workers' leader in the Philippines who supported Marxism-Leninism. He split with the Communist Party of the Philippines in 1991 due to ideological disagreements to form the Bukluran ng Manggagawang Pilipino (BMP). He was assassinated in 2001.