Nathan Fillion, who has been in a number of series that blend comedy with drama, including Firefly and Castle, but IMO, his standout dramatic TV role was in the horror genre: the evil Father Caleb in Buffy the Vampire Slayer.
Jack Klugman was good too. And the actor who played his tech assistant, Sam, also played Number 2 Son, Jimmy, in the old Charlie Chan mystery movies series, as the sidekick relief character.
Here’s a more obscure one: Vernee Watson is currently on Bob Hearts Abishola (comedy) and General Hospital (daytime drama). She’s awesome on both shows!
Max Gail was on Barney Miller and is also on General Hospital. And while we’re at it, so is Carolyn Hennessy (Cougar Town).