Mr Halligan died at the age of 84 at his home with family, following an illness.
The Irish economist and politician served as the general secretary of the Labour Party from 1967 to 1980, and was also appointed as a Senator and elected as a TD for Dublin South-West during this time.
He served as a Member of the European Parliament (MEP) from 1983 to 1984 and founded the IIEA, a think tank on European and international affairs. He also served as Chair of the Sustainable Energy Authority of Ireland.
Taoiseach Micheál Martin paid tribute to Mr Halligan, describing him as “a man who gave his life to politics and the public service with a deep commitment to the institutions of the state.”
“It is with deep sadness that I have learned of the passing of Brendan Halligan,” he said.
“Brendan was a European citizen who believed in the values of the European Union... he succeeded in facilitating a wide range of view on European and global issues. He succeeded in bringing many distinguished figures to Ireland.”
Labour Party leader Alan Kelly also paid tribute, saying: “Brendan Halligan was a committed socialist and a proud Labour man who I enjoyed speaking with until very recently about the future of our party.”
He said Mr Halligan was “a fascinating man with a formidable intellect and he was a leading light in the Labour Party who articulated the political vision for the party for more than a decade.”
He added that: “Through his time in Seanad Eireann, Dáil Éireann and the European Parliament, Brendan fostered a deep belief in socialism and in Europe and the European Union.
“He is also remembered for having founded the influential policy think tank, The Institute of International and European Affairs. The IIEA has successfully shaped political discourse around Ireland’s engagement with the European Union and its endearing success is a testament to Brendan Halligan’s vision and tenacity.
“I would like to extend my sympathies and those of my Labour colleagues to Brendan’s wife Margie, his family and friends at this difficult time.”
