Child (or teen-age) actors from other tv shows that appeared on Little House on the Prairie:

Mike Lookinland The Brady Bunch
Willie Aames Eight is Enough
Kim Richards Nanny & The Professor
Shannon Doherty Beverly Hills: 90210
Jason Bateman The Hogan Family
Todd Bridges Different Strokes

Radames Pera (Kung Fu)
Mitch Vogel (Yours, Mine & Ours, Bonanza)
Eric Shea (Yours, Mine & Ours, Poseidon Adventure)
Olivia Barash (Fame)
Tony Becker (The Other Side of the Mountain)
Ike Eisenmann (Return From Witch Mountain)
Ricky Segall (The Partridge Family)
Katy Kurtzman (Dynasty)
Steve Shaw (Knots Landing)
Jimmy McNichol (actor/singer/brother of Kristy)
Jennifer & Michelle Steffin (North & South)
Ham Larsen (The Wilderness Family movies)
Rossie Harris (Joey in Airplane!)

Honorable mention:

Melissa "Missy" Francis
Tracie Savage

who went on to respected TV careers - but in broadcasting.

Wow! You know your Little House on the Prairie!!!!!!!!!

Wow! You know your Little House on the Prairie!!!!!!!!!
:D

Sean Penn

Sean Penn
YES!! I knew I was forgetting someone. His father, Leo, was one of the show's directors.

Mike Lookinland (Bobby Brady on The Brady Bunch) appeared in the Season 4 episode "Times of Change". That's the ep in which Charles goes to Chicago to represent Walnut Grove at a Grange Convention. Mary goes along in order to connect with her boyfriend John (with whom she's kept in touch via letters). Turns out John is kind of a city boy now, and he has a new girlfriend, which he didn't tell Mary about. John escorts Mary to a dance (but he also has a date with his current girlfriend). Mary is devastated when she finds out that John was two-timing her.

On the train back to Walnut Grove, a boy enters and sits across from Mary and Charles. He introduces himself and indicates that he's moving to "Poplar Point" and it turns out he'll be a classmate of Mary's at the Walnut Grove school. Of course, I don't think we ever see him again on the show.

Here are some screen caps from that episode...

Also, Patrick Labyorteaux (adopted brother of Matthew, the boy who played "Albert"... ) was on Little House as well. IMDB credits him with appearing in 43 episodes as Andy Garvey, son of Jonathan Garvey (played by the late Merlin Olsen). Andy was friends with Laura.

Patrick later grew up to play "Bud" Roberts on JAG (IMDB credits him with appearances in 204 episodes).

It seems Mike Lookinland's cameo appearence was done for nostalgic purposes to play on Melissa's appearance on The Brady Bunch, as Bobby's school friend.

Sean Penn
Oh yeah! I remember how surprised I was to see Jeff Spicoli grinning like a turkey buzzard on fresh roadkill when Tinker Jones was making that bell.

Oh yeah! I remember how surprised I was to see Jeff Spicoli grinning like a turkey buzzard on fresh roadkill when Tinker Jones was making that bell.
:lol: :lol: :lol: :lol: :lol:

David Hollander (little Earl -What's Happening)
David Faustino (Bud Bundy - Married with Children)
They both appeared on the same episode during season seven playing brothers that Houston took in as his own.

Jimmy McNichol (Various Roles)
Olivia Barash (Fame)

Mike Lookinland (Bobby Brady on The Brady Bunch) appeared in the Season 4 episode "Times of Change". That's the ep in which Charles goes to Chicago to represent Walnut Grove at a Grange Convention. Mary goes along in order to connect with her boyfriend John (with whom she's kept in touch via letters). Turns out John is kind of a city boy now, and he has a new girlfriend, which he didn't tell Mary about. John escorts Mary to a dance (but he also has a date with his current girlfriend). Mary is devastated when she finds out that John was two-timing her.

On the train back to Walnut Grove, a boy enters and sits across from Mary and Charles. He introduces himself and indicates that he's moving to "Poplar Point" and it turns out he'll be a classmate of Mary's at the Walnut Grove school. Of course, I don't think we ever see him again on the show.

Here are some screen caps from that episode...
Melissa gives special mention of this moment in her book. :cool: :D

Tracie Savage who played Laura and Mary's best friend Christy Kennedy,
is best known as 'Debbie' from Friday the 13th Part III (hammock/knife threw chest).
She also has a career as a news co-anchor in California.

Sean Penn
YES
Sean Penn was in the Church Bell episode