He looked scary
Very few villains have looked fearsome on their own
Many have had to use exaggerated expressions to appear evil (Nambiar , famous South Indian villain for instance)
Others have needed to use a false gruff voice, costumes and menacing make up (Gulshan Grover for instance )
Even as a young man , there was something SCARY about his appearance that appealed to most directors
His natural voice had the baritone that added to the menace
To the best of my knowledge - only this guy from Thudarum managed to deliver so much menace naturally by just being there
Lead Actors marked him out
Most Actors WANTED HIM as the bad guy
Many Directors would FIRST TAKE PURI SAHABS DATES and then go for the Actors dates
For Ajooba , Shashi Kapoor and Bachchan personally visited Puris house and offered him ₹20 Lakh for acting as a villain and managed to extract 24 days for his scenes
He was similar to Goundamani & Senthil in Tamil except they were comedians and their dates were always sought after first
He demolished the careers of several villains like Prem Chopra or Ajit who had to move to positive roles to survive
Very rarely has Bollywood had such a man who simply looked menacing and had a menacing voice and was also a brilliant actor
Puri was the entire package
Lee Van Cleef of Hollywood is another who was menacing to look at, whose voice implied Villain and who rarely played good guy