According to sources, the couple were dating a few months before Q debuted an engagement ring Sunday at Golden Globes after-parties.
This would be the first marriage for Q and the second for McDermott, who was married for 13 years to Shiva Rose, with whom he has two children
E-mails to both stars' reps were not immediately returned.
On the Set of The Flash: Take a tour of S.T.A.R. labs!