Communist veteran and former Lok Sabha Speaker Somnath Chatterjee passed away at a private hospital in Kolkata on Monday following multiple organ failure.
He was 89.
The 10-time Lok Sabha MP is survived by his wife Renu, a son and two daughters.
Chatterjee passed away at around 8.15 am after his condition deteriorated following a mild heart attack on Sunday, a hospital official said.
"He suffered multiple organ failure and had stopped responding to treatment late last night," the official said.
His body was taken to the state assembly, where it was accorded a gun salute, and then to his residence.
Chatterjee, who was associated with the Communist Party of India-Marxist for most of his life, had donated his body to medical science.
It was handed over to the government-run SSKM Hospital later in the day.
He had suffered a cardiac arrest, systemic sepsis and renal failure along with respiratory problems and underlying diabetes, said a senior doctor, who was treating him.
Chatterjee suffered a mild heart attack yesterday morning but was revived.
The former speaker had suffered a haemorrhagic stroke last month.
Known as a Bhadralok (gentleman) Communist' like his mentor Jyoti Basu, Chatterjee had been under treatment for the last 40 days.
He was discharged from hospital just for three days after his health had shown signs of improvement.
However, his condition deteriorated last Tuesday and he had to be hospitalised again, the hospital official said.
Leaders across party lines condoled the death of Chatterjee, describing him as an outstanding parliamentarian who enriched Indian politics.
Condoling his death, Prime Minister Narendra Modi said he was a stalwart of Indian politics.
"He made our parliamentary democracy richer and was a strong voice for the well-being of the poor and vulnerable," he said.
Congress President Rahul Gandhi said Chatterjee was an institution who was greatly respected and admired by all parliamentarians across party lines.
"He was a remarkable human being, an eminent parliamentarian and a very clear headed speaker of the Lok Sabha. I convey my heartfelt condolences to the bereaved family," said former vice president M Hamid Ansari in a condolence message.
Recalling her long association with Chatterjee, Lok Sabha Speaker Sumitra Mahajan said he was from a different ideology, but was always kind to her.
CPI-M general secretary Sitaram Yechury, Left Front chairman Biman Bose and CPI-M state secretary Surya Kanta Mishra also paid their last respects to him. Senior leader Dravida Munnetra Kazhagam leader T R Baalu, BJP ministers S S Ahluwalia and Babul Supriyo also paid their last respects.
Chatterjee, who was speaker of the Lok Sabha from 2004 to 2009, was expelled from the CPI-M in 2008 for refusing to resign as speaker after his party withdrew support to the UPA-I government.
West Bengal Chief Minister Mamata Banerjee said the death of "Somnath Da" was a "great loss for us all".
State Governor K N Tripathi also expressed heartfelt condolences at the passing away of Chatterjee.
CPI-M leader Sujan Chakraborty said, "It's a big setback for us. Today, West Bengal lost its guardian. It's a big loss to the nation."
Chatterjee was a central committee member of the CPI-M, which he had joined in 1968.
His daughter Anushila said he had never said anything against the CPI-M, although he was "pained" after the Left party expelled him,
"We could see his agony and pain (after expulsion from the CPI-M). He loved the party throughout his life," Anushila said, adding that she had tried to make Chatterjee speak against the party, but her father never did it.
"We don't want any courtesy from them (CPIM). They have shown enough courtesy," she told a news channel.
Anushila, however, said many in the party kept contact with her father and some of them also came on Monday.
The CPI-M leaders, she said, proposed to place the party flag on Chatterjee's body. "(But) we did not agree, though my father might have been happy (if his body was draped with the party flag)."
Some of the West Bengal CPI-Mleaders, especially Biman Bose, faced the wrath of Chatterjee's son Pratap who said, "You used my father, now you have come to show sympathy. Stop this drama."
Talking to a news channel later, Pratap said he could never forget how Bose has spoken out against his father despite staying at their residence in New Delhi, whenever he visited the capital for party meetings.
"Biman Bose used to stay at our house in New Delhi but when my father was expelled from the party he had criticised my father. And the less we talk about Mr and Mrs Karat (Prakash & Brinda) the better," he said.
Bose declined to comment on the matter.
"He has lost his father today. He may have made some comments and it won't be right for me to make any comment," Bose said.
Senior CPI-M leader Nepaldeb Bhattacharya said many leaders visited Chatterjee in the last few years to convince him to rejoin the party, but the issue could not be resolved.
"It will be a lifelong regret for all of us that we could not take him back into the party. We are facing a tough situation today and it would have been of great help if he was with us. We tried to woo him back in the past, but failed in our efforts," he added.
When the body was taken out of his residence, CPI-M activists raised slogans - "Somnath Chatterjee amar rahe", "Red salute to Somnath Chatterjee.