The character was originally written for only one episode, but after her initial appearance, Morrison's chemistry with Mullally was an instant hit with fans, and she went on to appear in 68 episodes throughout the show's original run.
Morrison is survived by her husband of over 40 years, Walter Dominguez.
Her work as Rosario, season after season, was as nuanced and real as it was hysterical.
Tributes from the cast Morrison's castmates are heartbroken over the death fo their friend and they have all taken to social media to share their feelings.
Elsewhere, Grace Debra Messing and Karen Megan Mullally take a trip to Leo's cabin in Vermont in order to fix the plumbing - and uncover a secret pile of cash in the master bed.
Evil Lorraine returns and is joined by cameo appearances from a list of Hollywood celebs.