Deirdre Donnelly is an Irish actress of stage and screen. Best known for her work on television, from 1975 to 1979 she portrayed Kathy Peters on the long-running RTÉ drama serial The Riordans. From 1996-2001 she starred as Siobhan Mehigan on the BBC comedy-drama series Ballykissangel. She has had recurring roles on Vikings: Valhalla, Fair City, Brassic, The Virtues, Striking Out, The Frankenstein Chronicles, The Clinic, The Irish R.M., and Last of the Summer Wine.