Nassar made his acting debut in
K. Balachander's
Kalyana Agathigal (1985) portraying a secondary supporting role, before moving on to play villainous roles in
S. P. Muthuraman's
Velaikaran (1987) and
Vanna Kanavugal (1987). He played the protagonist in
Yuhi Sethu's
Kavithai Paada Neramillai (1987), though his breakthrough role came through his performance as a police officer in
Mani Ratnam's
Nayakan (1987). He subsequently became a regular in Mani Ratnam and
Kamal Haasan's ventures, appearing in pivotal character roles in
Roja (1992),
Thevar Magan (1992),
Bombay (1995),
Kuruthipunal (1995),
Chachi 420 (1997) and
Iruvar (1997). Nassar made his directorial debut with
Avatharam (1995), a film based on the backdrop of a folk art troupe. Starring
Revathi as his co-star, Nassar stated that the idea had come to him as a result of his childhood memories of watching
theru koothu being performed on the streets alongside his father. The film won critical acclaim, but failed to become a commercially successful venture. Soon afterwards, he made
Devathai (1997), stating he remembered a story he had first heard as a child, which became the "creative seed for this film" about reincarnation. He subsequently continued to work in films in the late 1990s, portraying a blind musician in
Rajiv Menon's
Minsara Kanavu (1997), a political leader in
Mani Ratnam's
Iruvar (1997) and as the father of a pair of separated twins in
S. Shankar's
Jeans (1998). In Malayalam cinema, he is noted for his roles alongside
Mohanlal in films like
Mukham (1990),
Butterflies (1993) and
Olympian Anthony Adam (1999). Some of the films that he has acted in Telugu include
Chanti (1992),
Bhageeratha (2005),
Athadu (2005),
Pokiri (2006),
Golimaar (2010),
Shakthi (2011),
Dookudu (2011),
Businessman (2012) and among others. Besides South Indian language films, he has acted in Hindi language films like
Chachi 420 (1997),
Phir Milenge (2004),
Nishabd (2007),
Rowdy Rathore (2012), (2016) and
Serious Men (2020) among others. He played Bijjaladeva, a pivotal role in the films
Baahubali: The Beginning (2015) and
Baahubali 2: The Conclusion (2017). He was seen as the mysterious antagonist in
Ponniyin Selvan: I (2022) and
Ponniyin Selvan: II (2023). He plays a two-faced character in the Hindi web series
The Jengaburu Curse (2023). ==Personal life==