Castiel's Sixth Death (Season 15, Episode 18)\n\n A bit before Supernatural's series finale, that happened, after Castiel finally confesses feeling romantic love for Dean. Sadly, The Shadow dragging him to The Empty is the last fans got to see of Cas.
Flashing forward, we learn that Sam has a son that he's named after his late brother, and we watch him grow up. Then, in a scene mirroring Dean's last, we see an elderly Sam pass away, with his loving son nearby. Ultimately, Sam and Dean are reunited in Heaven, where they can experience peace at last.