McDermott and his wife, Shiva Rose, married in 1995 and have two daughters.
The actor, who is best-known for starring on the TV legal drama, "The Practice," told Diane Sawyer in a 2001 interview that it was love at first sight when he spotted Rose in a coffee shop.
"I was in love with her right away," he said. "For her, it was a little longer, you know, a couple of years. But for me, it was right away. I guess it was grace."