De Lancie's is also known for his work on Star Trek as Q, as well as Stargate SG-1 and Breaking Bad.
The 64 yr young De Lancie will play Jake's grandfather, Royce Armstrong, who is described as powerful, yet recluse. Royce comes out of hiding to warn Jake about the disturbing conspiracy theories surrounding the events of 16 years ago and how the present-day circle is involved. We will first see grandpa Armstrong in episode 19.
Source: TV Guide