Karthik Sivakumar, better known by his mononymous screen name, Karthi is an Indian film actor who mainly works in the Tamil film industry. The actor made his debut with the 2007 movie, Paruthiveeran where he played the titlular character and won several accolades including a Tamil Nadu State Film Award and a Filmfare Award for Best Actor for his stellar performance. Karthi, over the years has starred in several other commercially successful and critically acclaimed movies like Paiyaa (2010), Naan Mahaan Alla (2010), Biryani (2013), and Madras (2014). Apart from acting, Karthi is also a philanthropist who actively participates in several social welfare causes and encourages his fans to do the same through Makkal Nala Mandram, a social welfare club that he inaugurated.

Early Life
Born on 25th May 1977, Karthi is the son of the renowned former veteran actor Sivakumar and Lakshmi Sivakumar. Actor, Suriya Sivakumar is his elder brother and he also has a young sister named Brindha. After completing his schooling, Karthi pursued his graduate degree in Mechanical Engineering from Crescent Engineering College, Chennai. After finishing his studies, Karthi worked as an Engineering consultant in Chennai, earning a remuneration of 5000 INR per month. However, after a few months of working as a consultant, he found the work to be too monotonous and he enrolled for Master of Science in Industrial Engineering at Binghamton University, New York, USA. While the actor was pursuing his master`s degree he also attended lectures on filmmaking at the State University of New York, which triggered his interest in acting. Before venturing out in acting, the actor worked as an assistant director to Mani Ratnam.

Personal Life
Karthik Sivakumar got engaged to Ranjini in April 2011 and two months later, the duo tied the knot on 3rd July 2011. The couple has a daughter named Umayaal who was born on 11th January 2013.

Movie Career
After completing his masters degree in the USA when Karthi returned to India, he met director Mani Ratnam who offered him a role in his film Aayutha Ezhuthu. However, Karthi declined the offer and chose to work as an Assistant Director for the Hindi version of the film titled Yuva. It was only after his father advised him to take up acting, he considered acting as a career option. Subsequently, when director Ameer approached him to play the titular role in Paruthiveeran, he accepted the offer because he felt the film was compelling. Upon release in January 2007, the film got wide critical acclaim and Karthi`s performance was well received by both the audience and the critics. He went on to his maiden Filmfare Award for Best Actor in Tamil.

Following the success of his debut film, Karthi next signed for Selvaraghavan`s adventure fantasy film Aayirathil Oruvan. The movie also featuring Reemma Sen and Andrea Jeremiah received mixed critical reviews but it emerged to be a huge commercial hit. The actor, next starred in Paiyaa alongside Tamannaah Bhatia, Milind Soman, and Sonia Deepti. The film was a commercial and critical hit and it earned Karthi a nomination at the 58th Filmfare Awards South for Best Actor.

In 2010, Karthi appeared in Suseenthiran`s thriller film, Naan Mahaan Alla where he played the role of a middle-class youth whose life is disrupted due to the sudden demise of his father. The film garnered good reviews and thus Karthi completed a hat-trick of hits. The actor next appeared in an action-drama film titled Siruthai. The movie directed by Siva was a remake of the 2005 Telugu film, Vikramarkudu and it was Karthi`s maiden outing in a double role. Upon release, the movie got mixed critical reviews but emerged to be one of the highest-grossing Tamil films of the year. For his next movie, director Suraj cast Karthi in his 2013 film, Alex Pandian alongside Anushka Shetty. Although the movie garnered great expectations, it got negative reviews. Karthi`s next movie, All in All Azhagu Raja released during Diwali 2013 and it also featured Kajal Aggarwal in the lead role. The film mostly received negative reviews and flopped at the box-office. After a series of flops, Karthi made a smashing comeback with Biriyani that released in December 2013. The movie directed by Yuvan Shankar Raja was released in Tamil and Telugu languages simultaneously. The movie opened to positive reviews and was a huge box-office hit.

Karthi`s first release in 2016 was a bilingual film, which was titled Oopiri in Telugu and Tozha in Tamil. The film directed by Vamsi Paidipally also features Tamannaah Bhatia and Nagarjuna Akkineni in the lead roles. The film got positive reviews and grossed more than 100 crore INR at the box office. His next was an action fantasy horror comedy titled Kaashmora. The film opened to mixed reviews and had a decent run at the box office. In 2017, for the first time, he collaborated with the celebrated director Mani Ratnam for Kaatru Veliyidai. The movie was not that well-received when compared to Mani`s previous movies. His next outing of the year was H. Vinoth`s Theeran Adhigaaram Ondru. His character Theeran Thirumaran DSP is widely regarded as one of his career-best performance and was declared super hit by the trade pundits. His 2018 projects include Kadaikutty Singam which is bankrolled by his elder brother Suriya`s home production 2D Entertainment. His 2019 release includes Dev, Kaithi and Donga. In 2021, Karthi appeared alongside Rashmika Mandanna in the action-drama film Sulthan. His 2022 releases include Vikram (2022), Viruman (2022), Ponniyin Selvan: I (2022) and Sardar (2022).