Nawazuddin Siddiqui is known for his versatile acting and has delivered some memorable performances in Bollywood. One of his most challenging roles was in Anurag Kashyap's neo-noir psychological thriller Raman Raghav 2.0. In this film, Nawazuddin played Ramanna, a psychopathic serial killer inspired by the real-life killer Raman Raghav, who operated in Mumbai during the 1960s.

The film depicts the cat-and-mouse chase between Ramanna and a corrupt cop, Raghavan, played by Vicky Kaushal. Nawazuddin's portrayal of Ramanna was chilling and unnerving, showcasing the depths of human darkness. He embodied the character with such conviction that it left a lasting impact on the audience.

Nawazuddin himself has stated that preparing for the role was a disturbing process. He had to understand and believe in Ramanna's twisted logic to convincingly portray him on screen. This involved delving into the mind of a person with a very different philosophy from a normal person. According to Nawazuddin, serial killers like Raman Raghav have a different mindset and follow their own logic, making it difficult for others to comprehend their actions.

To prepare for the role, Nawazuddin took extreme measures to get into the skin of his character. He even lived in a shady hotel in Lonavala for three days and convinced himself that he could easily kill someone. He shared in an interview that he felt disturbed during the process, as it had an effect on his mind.

Despite the dark nature of the character, Nawazuddin does not relate to violence in his personal life. In an interview, he stated, "I've never even raised my hand on someone...". This highlights the stark contrast between the actor and the character he portrayed, showcasing his ability to transform himself for a role.

Raman Raghav 2.0 premiered at the Cannes Film Festival in 2016, where Nawazuddin received a standing ovation for his performance. The film received critical acclaim for its storytelling, performances, and direction. Nawazuddin's portrayal of Ramanna was particularly praised for its ability to make the audience sympathize with a serial killer, creating a weird and conflicting feeling.

The role was mentally draining for Nawazuddin, and he even fell ill during the shooting. He was once found reciting the movie's dialogues while being half-conscious in a hospital. To unwind from the intense shooting experience, Nawazuddin would often visit his village in Muzaffarnagar and spend time farming. He believes it's important to separate reel from reality and that going back to his roots helps him stay grounded.

Nawazuddin Siddiqui's dedication to his craft and his ability to embody complex and challenging characters have made him one of the most respected actors in the Indian film industry. His role in Raman Raghav 2.0 remains a testament to his talent and his willingness to push boundaries to deliver memorable performances.