Chhailla Babu (Alternate name: Chhaila Babu) (English language: Cool Guy) is a 1977 Bollywood suspense thriller film. It was written and produced by Shomu Mukherjee and directed by Joy Mukherjee. Rajesh Khanna plays the title role of Chhailla Babu. It stars Zeenat Aman, Asrani, Om Shivpuri and Ranjeet. The film's music is by Laxmikant Pyarelal. It had a collection of 4 crores in 1977. The film became a superhit. This was the only film directed by Joy to be successful at the box office. and the success of Chhailla Babu gave a boost to the career of Khanna, who went through a bad phase between 1976 and 1978 at the box office.

This film seems to be very heavily inspired by the Cary Grant/Audrey Hepburn super hit film Charade.

The cinematographer in this film, Nariman Irani, while working on this film decided to borrow most of the plot of Chhailla Babu and shared a modified story idea to Chandra Barot, who made the new modified story as the film Don (1978).