Lost in Space
TV Series: Season 01; Episode #28: "A Change Of Space" (4/20/66)
Eight-year-old Will Robinson visits an alien ship, and returns with his IQ increased incredibly. Dr. Smith likes what he sees and goes to the ship himself. When he returns, he has been aged to well over 100 years.
Lost in Space
TV Series: Season 03; Episode #03: "Kidnapped In Space" (9/20/67)
The Robinsons encounter a group of aliens with limited control over time. Dr. Smith (who sure doesn't learn from his mistakes!) gets ideas of how he could use the device for his gain, and sets one gizmo to take him far back in time. Immediately he changes into a seven-year-old version of himself.
Lost In Space
TV Series: Season 03; Episode #19: "The Promised Planet" (1/24/68)
The Robinsons encounter a group of space teens who have turned their planet into a round-the-clock party. The make a proposal to Will Robinson: He can join in their party planet forever if he gives up his ability to grow older: The teens have no ability to age, and they want to know what it's like to grow. The Robinsons head off, with Will in tow. As they leave, the aliens' secret comes out... they are not "non-aging", they are regressing. And if they don't find someone to give them the ability to age soon, they will regress to their origins and cease to exist.
- (by Crash2014)