Nathaniel Marston was an American actor who plays Grant Vyro on Castle. Marston is probably best known as Michael McBain from 2004–07 on ABC's soap opera One Life to Live. On November 11, 2015, Marston died following complications from surgery after he was involved in a car accident near Reno, Nevada, that left him in critical condition on October 30, 2015. He was not wearing a seatbelt when his pickup truck flipped several times throwing him from the truck. He was only 40 years old.