From the wife of a king to the nanny of a serial killer...

Maria Doyle Kennedy, best known for playing Henry VIII’s first wife, Catherine Aragon, on The Tudors, has landed a role on season five of Dexter.

The Irish actress will help raise Dexter and Rita's kids in the fall, coming on board the Showtime hit as a part-time nanny. Guess Deb and Dexter can't do it by themselves, after all.

Julia Stiles and Shawn Hatosy will also play important roles on season five.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.