Thackeray was born in Pune on 23 January 1926 to Ramabai and Keshav Sitaram Thackeray (also known as ‘Prabodhankar’). He was the eldest of nine siblings and belonged to the Marathi Chandraseniya Kayastha Prabhu (CKP) community. Keshav was a progressive social activist and writer who was involved in the Samyukta Maharashtra Movement of the 1950s that argued for the creation of a unified state called Maharashtra for Marathi-speaking areas with Mumbai as its capital. Keshav was said to have supported the use of strategic violence as means to achieve that objective and left the movement because of his stance against communists. Keshav’s political philosophy inspired Thackeray.