Shivaji Rao Gaikwad (রজনীকান্ত), known professionally as Rajinikanth, is an Indian actor who predominantly works in Tamil cinema. In a career spanning over five decades, he has done 170 films that includes films in Tamil, Hindi, Telugu, Kannada, Bengali, and Malayalam. He is widely regarded to be one of the most successful and popular actors in the history of Indian cinema. Known for his uniquely styled mannerism and one liners in films, he has a huge fan base and a cult following. The Government of India honoured him with the Padma Bhushan in 2000 and the Padma Vibhushan in 2016, India's third and second highest civilian honours respectively, and the Dadasaheb Phalke Award in 2019, the highest Indian award in the field of cinema, for his contributions to Indian cinema. He has won numerous film awards including one National Film Award, seven Tamil Nadu State Film Awards, a Nandi Award, one Filmfare Award and two Maharashtra State Film Awards.

Rajinikanth was born as Shivaji Rao Gaikwad on 12 December 1950 in a Marathi family in Bangalore, Mysore State (present day Karnataka). His mother was a homemaker, and his father Ramoji Rao Gaekwad was a police constable. His ancestors hailed from Mavadi Kadepathar, Pune district, Maharashtra. He is the youngest of four siblings in a family consisting of two elder brothers (Satyanarayana Rao and Nageshwara Rao) and a sister (Aswath Balubhai). After his father's retirement from work in 1956, the family moved to the suburb of Hanumantha Nagar in Bangalore and built a house there. He lost his mother at the age of nine.

Rajinikanth had his primary education at the Gavipuram Government Kannada Model Primary School in Bangalore. As a child, he was "studious and mischievous" with a great interest in cricket, football and basketball. During this time, his brother enrolled him at the Ramakrishna Math, a Hindu monastery set up by the Ramakrishna Mission. In the math, he was taught Vedas, tradition and history, which eventually instilled a sense of spirituality in him. In addition to spiritual lessons, he also began acting in plays at the math. His aspiration towards theatre grew at the math and was once given an opportunity to enact the role of Ekalavya's friend from the Hindu epic Mahabharata. His performance in the play received praise from the Kannada poet D. R. Bendre. After sixth grade, Rajinikanth was enrolled at the Acharya Pathasala Public School and studied there till completion of his pre-university course. During his schooling at the Acharya Pathasala, he spent a lot of time acting in plays.

It was speculated that Rajinikanth would enter politics in 1995. He decided against it and declared that if he entered politics now, it would result in a lot of confusion and that he would not be able to serve the people and fulfil their expectations. However, he added that if Chief Minister J. Jayalalithaa's party returns to power in the 1996 Tamil Nadu Legislative Assembly election, "even God cannot save the people of the State". Rajinikanth went on to wholeheartedly support the Dravida Munnetra Kazhagam (DMK) and Tamil Maanila Congress alliance and asked the people of Tamil Nadu and his fans to vote for that alliance. This alliance had a complete victory in the elections. He also supported the same alliance in the 1996 and 1998 Indian general elections.

Later in 2004, Rajinikanth said he would personally vote for the Bharatiya Janata Party (BJP) but would not extend his support to any front during the upcoming Indian general election. The party, however, failed to win any seats in Tamil Nadu in the Lok Sabha.

Rajinikanth is widely regarded as one of the most popular actors in the history of Indian cinema. His popularity has been attributed to his distinctively delivered dialogue and eccentricities showcased in his movies, alongside his political pronouncements and charitable work. Many also cite reasons for Rajinikanth's popularity as coming from his larger-than-life super-hero appearance in many films, supported by gravity-defying stunts and charismatic expressions, all while attempting to maintain modesty in real-life. Almost every film of Rajinikanth has punchlines delivered by him in a distinctive style, and these punchlines often have a message or even warn the film's antagonists.

Rajinikanth is one of the highest-grossing actors in Tamil cinema history. After opening his first official Twitter account in 2014, Rajinikanth received over 210,000 followers within 24 hours, which according to The Economic Times was deemed by social media research firms as the fastest rate of followers for any Indian celebrity, as well as among the top-10 in the world. In 2015, a film about his fandom, For the Love of a Man, premiered at the 71st Venice International Film Festival.