Mamata Banerjee's trusted Lieutenant has been with the Trinamool Congress since its founding, particularly during the party's movements against land acquisition at Singur and Nandigram, but has always preferred keeping a low profile.
57-year-old Mukul Roy, who was not into politics initially, was the non-executive director of the United Bank of India from 2002 to 2005.
He became a member of the Rajya Sabha from West Bengal in April 2006 and in August the same year was appointed member of the Committee on Urban Development as well as a member of the Consultative Committee for the Ministry of Home Affairs.
In April 2008, he was appointed his party's all India General Secretary and in May 2009 became Minister of State in the Shipping Ministry.
When Mamata Banerjee resigned as the Railway Minister after becoming Chief Minister of West Bengal, he was handed additional charge of the Railway Ministry.
On July 11, 2011, when Prime Minister Manmohan Singh directed Mr Roy to visit the site of derailment of the Guwahati- Puri Express in Assam, he openly defied him. He was relieved of the Railway portfolio in a cabinet reshuffle on July 12 the same year.
Born on April 17, 1954 at Kanchrapara near Kolkata in North 24 Parganas district to late Jugal Nath Roy and Rekha Roy, he did his schooling at the Harneet High School at Kanchrapara. He did his B.Sc (Part I) from Calcutta University.
He actively participated in drama, quiz and inter-school science exhibitions during his student days and was a member of the Bharat Scouts and Guides and regularly took part in camps.
He also served in various community development projects including eradication of illiteracy, providing free education for the poor and civil defense training.
Mukul Roy married Rekha on August 14, 1980 and has a son. His favourite pastime is watching one-day cricket matches and is also a huge fan of football and the Mohun Bagan Club.