Satinder Kumar Sikka is an Indian nuclear condensed matter physicist, crystallographer and a former Scientific Secretary to the Principal Scientific Advisor of the Government of India. He is known to have played a crucial role, along with Raja Ramanna, Rajagopala Chidambaram and Basanti Dulal Nagchaudhuri, in the design and development of a Hydrogen Bomb by India, which was tested at the Pokhran Test Range in May 1998, under the code name, Operation Shakthi. He was also involved in the Smiling Buddha tests, conducted in 1974. He was awarded the fourth highest civilian award of the Padma Shri, by the Government of India, in 1999.