Martin McGuinness died early this morning at Derry's Altnagelvin Hospital.
McGuinness, 66, had been diagnosed with a rare heart disease in December.
He led the party into power-sharing with the DUP in 2007 and served as deputy first minister alongside Ian Paisley, Peter Robinson and Arlene Foster.
He became Sinn Féin's chief negotiator in the peace process.
In 2011, Mr McGuinness contested the presidential election which was won by Michael D Higgins.
Deputy Pearse Doherty knew Martin McGuinness for 24 years. He said that his death was "a devastating blow" to the Sinn Féin party. He paid his condolences to the McGuinness family.
"We've lost a true giant, a giant among men," Deputy Doherty said.
Martin McGuinness had close affiliations with Donegal. His mother was from Buncrana and McGuinness was a frequent visitor to the Gaeltacht area.
Senator Pádraig MacLochlainn said that Martin McGuinness was Ireland’s Nelson Mandela, a man who led by example and was committed to peace.
Tributes have been paid by leading political figures this morning.
Subscribe or register today to discover more from DonegalLive.ie
Buy the e-paper of the Donegal Democrat, Donegal People's Press, Donegal Post and Inish Times here for instant access to Donegal's premier news titles.
Keep up with the latest news from Donegal with our daily newsletter featuring the most important stories of the day delivered to your inbox every evening at 5pm.