Lord (Ken) Maginnis failed to win re-election to Dungannon council having held a seat for some 20 years.
He was not defending his former seat, having moved to another district in an attempt to pick up another seat for the Ulster Unionist Party.
The former Fermanagh-South Tyrone MP, now a member of the House of Lords, last night refused to comment on his chances in the forthcoming election of replacing David Trimble as party leader.
With Lady Sylvia Hermon, the party's sole member of the House of Commons, retaining an open mind on the leadership question, Lord Maginnis and Lord Kilclooney - the former Mr John Taylor - have been mentioned as possible leaders, at least in the short term.
Lord Maginnis said last night he would neither seek nor refuse the leadership if that was his party's wish. His defeat in the local government election was not the only high-profile loss.
In Belfast, Billy Hutchinson, David Ervine's Progressive Unionist Party colleague, lost his council seat in north Belfast.
In Antrim, Sinn Féin's Martin Meehan failed to win a council seat while the SDLP's Donovan McClelland was also eliminated. Mr McClelland lost his South Antrim seat in the October 2003 elections to the suspended Stormont Assembly.
Joe Byrne, a former SDLP Assembly member in Omagh, lost his council seat. His fate is being linked to the overall success of Dr Kieran Deeny, an independent, anti-hospital closure candidate, and to local dissent within the SDLP.