Arun Kumar Chattopadhyay (3 September 1926 – 24 July 1980), known professionally as Uttam Kumar (Bengali pronunciation: [ut̪ːɔm kumar]), was an Indian actor, director, producer, screenwriter, composer and playback singer who predominantly worked in Bengali cinema. Widely regarded as one of the greatest and most successful actors in the history of Indian cinema, Kumar dominated Bengali cinema from the 1950s throughout the 1970s, being referred to as "Mahanayak" (Bengali for "The Great Hero"). His accolades include five National Awards and four Filmfare Awards.

In a career spanning over five decades, Kumar worked in 211 films, till his death in 1980. After a few years of acting in plays, he made his film debut in the 1948 film Drishtidan in a supporting role, produced by M. P. Productions. By the early 1950s, he had graduated to lead roles and had his first box office hit with Basu Paribar (1952), following a series of unsuccessful ventures. He first gained popularity with Sharey Chuattor (1953), where he starred opposite his frequent co-star Suchitra Sen. He consistently starred in top-grossing films from the mid-1950s to the 1960s, such as Champadangar Bou, Agni Pariksha, Shap Mochan, Sabar Uparey, Sagarika, Ekti Raat, Harano Sur, Pathey Holo Deri, Indrani, Maya Mriga, Saptapadi, Bipasha, Bhranti Bilash, Deya Neya, Kokhono Megh, as well as some of his most acclaimed performances include Upahar, Raat Bhore, Saheb Bibi Golam, Shyamali, Marutirtha Hinglaj, Bicharak, Abak Prithibi, Kuhak, Khokababur Pratyabartan, Jhinder Bondi, Sesh Anka, Uttarayan, Jatugriha, Nayak, Chowringhee, Chiriyakhana and Antony Firingee. He achieved further superstardom and appreciation in the 1970s, for starring in several successful ventures with different genres, including Nishi Padma, Rajkumari, Bilambita Loy, Dhanyee Meye, Chhadmabeshi, Stree, Mem Saheb, Andha Atit, Bon Palashir Padabali, Amanush, Sanyasi Raja, Agnishwar, Mouchak, Bagh Bondi Khela, Sabyasachi, Ananda Ashram, Bandie, Nishan, Dhanraj Tamang, Brojobuli, Pankhiraj, Dui Prithibi, Ogo Bodhu Shundori and Kalankini Kankabati. Apart from acting, Kumar showed his versatility in another fields, including as a director and screenwriter of films such as Sudhu Ekti Bachhar, Bon Palashir Padabali and Kalankini Kankabati, as a composer in Kal Tumi Aleya and Sabyasachi, and as a singer in Nabajanma.

Kumar was the first recipient of the National Award in the Best Actor category for his work in Antony Firingee and Chiriyakhana. He is the namesake of Mahanayak Uttam Kumar metro station in Tollygunge and the Mahanayak Samman Award given by the Government of West Bengal.

Uttam Kumar was born as Arun Kumar Chattopadhyay on 3 September 1926 at his maternal home, situated at 51 Ahiritola Street in northern Calcutta (now Kolkata), in the Bengal Province of British India (now in West Bengal, India). His father was Satkari Chattopadhyay, a Hindu Brahmin from Hooghly district, and his mother was Chapala Devi. Initially he was named "Uttam" by his maternal grandfather, although his mother did not like this name, so the name "Arun" was given. Sripurna Sanyasi, the spiritual master of his maternal family, predicted that the entire country would recognise him by the name "Uttam", seeing his smile.

Belonging to an extended middle-class family, Kumar's father was a film projectionist in Metro Cinema. He had two brothers, Barun and Tarun, of which the latter also became an actor. His ancestral home was at 46/A Girish Mukherjee Road in Bhabanipur, where his interest in acting grew by watching the Jatra reharsed and performed by the group Suhreed Samaj, founded by his father and uncle.

Kumar first studied in Chakraberia High School, where his first acting opportunity came at the age of five in the Gayasur play, which awarded him a medal, in the child role of Gayasur. In 1936, he found a theatre group called Lunar Club, along with his friends, whose first production was Rabindranath Tagore's Mukut. It turned out to become a huge success, that the artists were offered a room for their rehearsals at a neighbour's home. His father selected him to play the role of Balarama in Suhreed Samaj's stage production Brajer Kanai.

In 1940, Kumar moved to South Suburban School (Main), where he passed matriculation with second division in 1942. He joined Government Commercial College (now Goenka College of Commerce and Business Administration) for his higher studies in 1943, where he passed B. Com standard, and joined Calcutta Port Trust as a clerk in the cash department, with a monthly salary of ₹275. In 1943, Kumar also donated ₹1,700 to the fund of Indian National Army, which was earned from a special stage production of Bankim Chandra Chatterjee's Anandamath by Lunar Club.

Kumar took classical music training from Nidanbandhu Banerjee in his childhood. An admirer of Johnny Weissmuller, he was the champion of hundred yards Freestyle at Bhabanipur Swimming Association for three consecutive seasons. He also learned yoga, wrestling and Lathi Khela, a traditional Bengali martial art. As a skilled footballer, Kumar used to play in the right-back position and was a lifelong Mohun Bagan supporter. At the same time, he was equally interested in playing volleyball and cricket.