She only appeared in person twice in "Glee", once in the pilot and on another occasion in 2015, as her character's image appeared in a trophy case commemorating her life.
A quote from Lillian: "By its very definition, Glee is about opening yourself up to joy," was visible on a plaque and helped inspire Will, played by Matthew Morrison, to pursue his dream of becoming the glee club director.
Galloway Heitz's character was herself a former head of glee club at McKinley High, reports variety.com.
Galloway Heitz also played the character of Mildred in a 2009 episode of "The Big Bang Theory", and Claire in a 2012 episode of "Shameless". Her other TV credits include "Grey's Anatomy", "ER", "Monk", "Prison Break", "CSI: Crime Scene Investigation", "Without a Trace" and "Early Edition".
On the film side, Galloway Heitz starred alongside Richard Farnsworth and Sissy Spacek in David Lynch's 1999 road movie "The Straight Story".
She also played a nurse opposite Lindsey Lohan in the 2007 psychological thriller "I Know Who Killed Me".
In 2001, Galloway Heitz played the intriguingly named Dinah the Drunk in the French-American movie "Just Visiting" with Jean Reno and Christina Applegate. The film was a remake of the wildly popular French fantasy comedy "Les Visiteurs," but unlike the original, it turned out to be a box-office flop.
She is survived by her daughter Amie (Rod) Richardson, and three grandchildren.
( With inputs from IANS )