All the "That '70s Show" OGs Who Pop Up in "That '90s Show"

Kutcher's Kelso makes his grand return at the end of the season premiere when, during a visit to the Forman household, it's revealed that he's Jay's father. Kelso then pops back up at the house with his on-and-off-again high school girlfriend-turned-wife, Jackie (Kunis) — who's also Kutcher's wife in real life.