The TUV councillor was absent from Monday night’s meeting of full council, a rare occurrence in his three decades of serving the borough.
Former Mayor of Ballymena, Alderman Maurice Mills said his thoughts and prayers were with Mr Gillespie and his family.
Fellow TUV Councillor Mr Timothy Gaston told the chamber that Roy’s operation had taken less time than expected and he was sitting beside his bed and hoping to get home shortly.
Mr Gaston said: “He has been sadly missed, especially for the contribution he makes.
“Since I came into council the experience and help he has given me has been second to none and I look forward to him sitting alongside me once again.”
Councillor Declan O’Loan offered his best wishes and said he was “pleased to hear the good report.”