Prem Chopra was the most distasteful, lecherous, and downright evil 'Bad Guy' of 70s and 80s Bollywood cinema. Prem Chopra made the character of the bad guy frighteningly real. I have heard people say they are terrified even by the mention of his name. Certainly after watching one of his performances many would not want to be left alone in a room with him. In countless Bollywood films (he has acted in over 400 movies) Prem Chopra played the heavy to the hilt.
Having started out as a 'Hero' in the 60s Prem discovered his true forte as a bad guy in the early 70s. His slimy characters in "Purab Aur Pachhim" , "Hare Ram Hare Krishna" , "Bobby" [1973}, and "Teesri Manzil"  are all time classic performances of Bollywood cinema. There is a hateful envy and sadistic perversity that is almost palatable in his portrayals.
Along with Pran and Jeevan, Prem Chopra ruled the bad guy roost of 70s Hindi Cinema, no one else even came close. Prem Chopra is also one of the few Bollywood actors to have an 'official web site'.( I have made a link to it below.) It is a very good web site, well organized with lots of great information on the man. In searching on the web I also discovered a short story written by him that was first posted on an online magazine. In fact there are at least a handful of online articles written by Prem Chopra on the web, ranging from interviews, to short stories, to travels descriptions of the Uttar Pradesh region of India.
The scary psychopath of Bollywood turns out to be a well read and articulate man of letters. Today Prem Chopra is still acting in films and is also a big star on Indian Television. He does not always play the heavy and bad guy, but Prem Chopra will always be remembered as the enemy who is your worst nightmare.