The veteran theater actor recently starred in Plaza Suite opposite Matthew Broderick and Sarah Jessica Parker.
McGrath died at his home in Bloomfield, N.J., on Thursday, a representative confirmed to EW.
A cause of death was not revealed.
Michael McGrath.Kempin/WireImage for Tony Award Productions
“Warm hugs to all theSpamalotfamily and very happy memories of a lovely man.”
Alongside her caption, Murin shared a snapshot of McGrath holding her daughter, Lorelai.
as he crooned her a lullaby."
