Bhatnagar is a common surname used mostly in northern India among the Kayastha

Kayastha

Kayastha or Kayasth or Kayeth is a caste or community of Hindus originating in India. Kayastha means "scribe" in Sanskrit, and has traditionally denoted members of the writer caste....

 caste of Hindus. They came from the Second son of the first wife of Lord Chitragupta

Chitragupta

Chitragupta is a Hindu god assigned with the task of keeping complete records of actions of human beings on the earth. Upon their death, Chitragupta has the task of deciding heaven or the hell for the humans, depending on their actions on the earth...

, the recordkeeper of the God of Death, Yama

Yama

Yama , also known as Yamarāja in India and Nepal, Shinje in Tibet, Yanluowang or simply Yan in China, Yeomla Daewang in South Korea and Enma Dai-Ō in Japan, is the lord of death, in Hinduism and then adopted into Buddhism and then further into Chinese mythology and Japanese mythology. First...

. Chitragupta http://www.sacred-texts.com/hin/gpu/gpu16.htm. Shree Chitraksh (Bhatnagar):Disciple of sage Bhat. Wife was Bhadrakalini. Worshipped Jayanti. Maharaj Chitraguptji sent Shree Chitraksh to establish a Kingdom in the region of Bhat river at Bhattdesh and Malwa. They established Chittor and Chitrakoot. He settled then there and his progeny came to be known as Bhatnagar.

Notable Bhatnagars

• Sir Shanti Swarup Bhatnagar, Indian scientist
• Prabhu Lal Bhatnagar
  Prabhu Lal Bhatnagar
  Prabhu Lal Bhatnagar , commonly addressed as P. L. Bhatnagar, was an Indian mathematician known for his contribution to the Bhatnagar-Gross-Krook collision model used in Lattice Boltzmann methods .-Early years:...
  
   - Padma Bhushan
  Padma Bhushan
  The Padma Bhushan is the third highest civilian award in the Republic of India, after the Bharat Ratna and the Padma Vibhushan, but comes before the Padma Shri. It is awarded by the Government of India.-History:...
  
   scientist, Indian mathematician
• S K Bhatnagar, former defence secretary of India
• Shivani Bhatnagar
  Shivani Bhatnagar
  Shivani Bhatnagar was a journalist working for the Indian Express newspaper. Her murder on January 23, 1999 became a scandal that reached into the top levels of Indian politics. Indian Police Service officer Ravi Kant Sharma was charged with the murder by the Delhi Police, who investigated the case...
  
  , journalist
• Dipti Bhatnagar, Actress
• Vibha Bhatnagar
  Vibha Bhatnagar
  Vibha Bhatnagar is a London-based entrepreneur. Born in India on 11 September, she is a seasoned entrepreneur with a track record of converting radical business concepts to real businesses. She has also been a part of the Film Industry for over two decades....
  
  , Film producer and entrepreneur