'Supernatural' spoilers: Gil McKinney to play John Winchester's father in time-travel episode

The "Supernatural" boys don't have too much luck when it comes to grandparents -- their maternal grandfather, Samuel, spent most of Season 6 working against them, and was even willing to kill them. Now, we'll meet their paternal grandfather -- but there's a twist!

"Friday Night Lights'" Gil McKinney is set to star as Henry Winchester, John Winchester's father. (Yes, he played Julie Taylor's married teacher who she slept with. Excellent!)

He'll appear in the time travel episode we told you about earlier this month. In 1958, Henry was involved in an anti-demonic cult. Apparently, it runs in the family. Interestingly enough, Henry became involved in the cult in the interest of protecting his 7-year-old son, John.

Cool, no? Henry is described as "Robert Downey Jr. meets Cary Grant" -- dapper, smart, and a little arrogant.

Things went south for him when he accidentally opened up a time portal and found himself hurtled into the present-day. He didn't time-travel alone, though -- he finds he was followed through the portal by 28-year-old Josie Sands, a sexy, strong Katharine Hepburn type... with a secret. Sam and Dean encounter Henry and Josie in a hunt for a bloodthirsty demon. Given their family history, they're pretty wary of him, but he may provide some compelling insight about the ever-enigmatic John WInchester.

The casting was first reported by Huffington Post.