Toddy O’Sullivan, a former Labour TD and minister of state, has died aged 87.
A major political figure in Cork in the 1980s and 1990s, Mr O'Sullivan served as a TD in the city for 16 years and was lord mayor from 1980 to 1981.
Taoiseach Micheál Martin described him as a "mentor and friend".
"I am deeply saddened to learn of the passing of Toddy O’Sullivan," Mr Martin said in a statement.
"As a Minister of State, TD, Lord Mayor and City Councillor, he served his city and his country with passion, integrity, dignity, and total commitment throughout his life.
"From my early days serving on Cork City Council in 1985, Toddy was a mentor and friend in politics.
"He understood the importance of a cross-party approach for the benefit of the people.
"Whether in his capacity as city councillor, TD or Minister of State, he worked hard to advance the interests of the people of Cork and the country.
"We will miss him."
Paying tribute on Sunday morning, Labour leader Alan Kelly recalled getting to know Mr O'Sullivan as a student in University College Cork and said he often visited him at his home over the years.
"Starting from a low electoral base, Toddy worked assiduously to build the Labour Party in Cork and between the local elections of 1974 and 1979 he more than doubled his first preference vote to 1,199 in the South West ward of Cork Corporation. He went on to serve as a very successful Lord Mayor of the city he loved in 1980.
“A staunch trade unionist, he was always on hand to support his colleagues in the Post Office Workers Union and was rooted in his community in the Barrack Street area in the south inner city."
A stalwart of the Labour Party in Cork, Mr O'Sullivan first stood for the Dáil in the 1979 Cork City by-election after the death of Patrick Kerrigan.
He topped the poll in 1981 and was returned to the Dáil a further five times.
During his time in the Dáil, Mr O'Sullivan served twice as a minister of state, first in the Department of the Environment, and later in the Department of Tourism and Trade.
"Toddy leaves behind a distinguished record of service, nationally and locally, and will continue to be an inspiration to future generations of Labour activists in Cork," said Mr Kelly.
Cork East Labour TD Sean Sherlock said:
“There are not many public representatives in Irish politics who are known ubiquitously by their first name. Toddy was one. He was highly respected across the city and county. He represented his people to the best of his ability. Our hearts go out to his family.
Independent city councillor, Mick Finn, also a former Lord Mayor, said: A native of Barrack St and a past pupil of Greenmount NS, Toddy was an icon of Cork public life who served his city - and particularly Cork South Central - so well as a councillor, Lord Mayor, TD and junior minister.
“One of those special natives widely known by his first name, Toddy gave me plenty of advice when I started off in the council and particularly when I was honoured to follow in his footsteps as Árdmheara.
“Cork has lost a giant of Cork politics, community and trade unionism…condolences to his wife Esther, family, friends and Labour Part colleagues past and present.”