In his movies, Rajinikanth has defied science. In real life, he has defied logic to remain a superstar for as long as anyone can remember.

"A star requires great luks, good height, versatile acting, six pack body, etc and if one has none of the above he will become super star rajini. "
-Director Ram Gopal Varma on Twitter

At 61, he looks anything but a hero - he is dark, almost bald, and usually appears unshaven and unkempt in public - and yet even the most successful of stars would envy his success. He scales a new box office height with each release, inspiring one-liners that are treated as folklore.

Sample this: When Rajinikanth writes a cheque, the bank bounces. His latest film Enthiran has been judged this year's biggest grosser in India - ahead of Dabangg and 3 Idiots. It debuted in the top 10 in the UK. As veteran filmmaker K Balachander, who introduced him way back in the 1970s, wrote in a letter to Enthiran's director, Shankar, "I can modestly say that I know Rajinikanth. I christened him. Also converted him into an actor. After me, a few other directors made him a hero. After that, Mani Rathnam (Thalapathy) and Suresh Krishna (Baasha) made him a commercial certainty. But you have made him a cinema conglomerate."

On October 1, when Enthiran opened with 2, 250 prints, it was as if Diwali had arrived a month early in Chennai. People cutting across age groups, social strata, caste affiliations and gender headed out to theatres before daybreak to burst crackers and celebrate the first offering to their 'thalaivar' (leader) in two years.

Rajinikanth, born Shivaji Rao Gaekwad, came into prominence in the 1970s and along with Kamal Haasan filled up the void left by M G Ramachandran and 'Sivaji' Ganesan. Though he was initially noticed for his 'baddie' roles in K Balachander's Moondru Mudichu and Bharathiraaja's 16 Vayadinile, he soon went on to become a rage with his cigarette tricks and stunts. Suddenly, here was a hero who talked to the audience and not at the audience. Some one who looked and spoke like them. It was a cathartic moment for the Tamil viewer. The only other hero who was capable of generating such hysteria, M G Ramachandran, had moved on to politics. The position he left behind in Tamil cinema was vacant. And thus a new phenomenon was born.

Rajinikanth has come a long way since, in a career spanning more than 150 films in five languages (not to mention the odd English and Bengali film as well). His ability to connect with different generations and transcend the North-South divide remains a bit of an enigma. Some say he has an unerring knack for picking the right subjects. Others say his characters tend to personify a set of qualities that make him a universally endearing star. Rajinikanth clearly refuses to take himself too seriously on screen, often making fun of his own image, a trait that the audience finds adorable. A good example of this was Sivaji the Boss, in which he tries numerous methods to bleach his dark skin.

Those who know him well say the key to his astounding and enduring success is his humility and simplicity. Suresh Krisshna, who directed the hit Annamalai for the superstar, recalls that whenever he arrived for a shoot, Rajini would get up from the chair as a mark of respect to the director. "He does not have to do that, but such humility is ingrained in him, " adds Balachander, who first spotted Rajini among some students of the Madras Film Institute.

And then there is his professional conduct. No temper tantrums, no record of having turned up for work sloshed, no demands for special meals, no walking off to the air-conditioned trailer after a shot. "He would always sit under an umbrella and a fan, and watch the rest of us work," recalls actor Khushboo who was paired with him in five films.

Rajini rarely makes mistakes in choosing a film, say directors. Once a story is narrated, his characteristic response is, "I will think about it. " And once he signs up, he gives it all that he has. "The toughest thing to get from Rajnikanth is his call sheet. But once he commits to a film, his dedication and involvement is complete, " says director S P Muthuraman whose debut film with the superstar, Bhuvana Oru Kelvikkuri, was also the first film in which Rajini played the hero.

After the day's shooting is wrapped up, he usually calls up the director the same night: "How was my performance? What more should I do?" On occasion, he has been known to come up with winners himself, like Padayappa. "The story of a woman falling in love with the hero and then turning vengeful when he spurns her, was his idea, and it worked brilliantly, " says K S Ravikumar, who directed the movie.

As Naman Ramachandran, who manages South Asia for Variety, says, "Here is a hero who in his offscreen appearances is saying, 'this is how I look in real life, yes I am balding, I am usually unshaven, I have a bit of a paunch, and what does that tell you? That I am human like you. ' Southern Indian audiences appreciate this dichotomy - the hero is human like them, but is a superman on the big screen."

Agrees Vishnuvardhan, who remade Billa in 2007 with actor Ajith. "People don't care how he looks in real life. His on-screen image is much bigger than his off-screen image. He has an aura that can attract people . . . the kind of energy he delivers on screen is unbelievable. It is not about performing, it is much beyond that."

He adds, "Billa, which itself was a remake of Amitabh Bachchan's Don, worked in Tamil only because of Rajini. If you talk of Rajini's style, Billa had it completely. Natural style, not made up . . . not artificial. I really enjoyed the movie when I was growing up. That is why I wanted to remake it. " Rajinikanth's style and chutzpah have been major reasons for his ever-growing fan base. The introductory fights and songs add to his allure. An 'intro fight and song' were added to the Malayalam original Manichitrathazhu when it was remade in Tamil as Chandramukhi;the same was the case with Thenmaavin Kombathu when it was remade into Muthu. The only exception to this rule was Enthiran, perhaps because the director could not find a slot to include them.

At 61, Rajini remains confident of himself and his audience;he is having fun and it shows on screen. And though the days of the cigarette being tossed up and lit mid-air are long gone, he is still enjoying the anti-hero roles. In his latest outing, he plays an evil robot who abducts his creator's girlfriend to create a new species called 'Robo Sapiens';and he bleats like a goat to make fun of her meek boyfriend.

As director Balachander wrote in his letter to Shankar after watching the movie, "I introduced Rajini as a bad man. You have made him worse. Wonderfully worse."