My Week with The Sunny Side Up Show: When a Celebrity Comes to Visit

 

Images from 2015

Madeline Fretz - Back in the early days, The Sunny Side Up Show often had guest appearances from Sprout characters. According to this Sprout for Parents article, when Team Sprout came up with the theme for each week, they brainstormed the guest ideas they would like to have. They tried to book a guest as far in advance as possible, usually a few months before their actual appearance, because their schedules tended to fill up very quickly.

Let's start with the Sesame Street appearances. Sesame Street had the most guest appearances on the block.

Image from Muppet Wiki

Image from Nolan Hong

Image from Jeremy Wintroub

• Big Bird (Matt Vogel, who currently plays him to this day) was the first guest. He appeared in the pilot from September 2007 and in a few promo pictures.
• Prairie Dawn (Fran Brill, who played her until 2014) appeared for Valentine's Day 2008 with Kelly Vrooman and Chica. Viewers could get to call her live.
• Oscar the Grouch (Caroll Spinney, who played him until 2018) appeared for Earth Day 2008 with Sean Roach and Chica. The character returned for Oscar Weekend 2014 where he and Chica gave Dennisha Pratt a manicure, and again in 2015 with Kaitlin Becker and Chica (he was performed by Eric Jacobson, who currently plays him to this day, here). The latter was the last time a Sesame Muppet appeared on the block, as the show stopped airing later that year.
• Super Grover (Eric Jacobson, who currently plays him to this day) appeared for New Year's Eve 2008 and Day 2009 with Kelly Vrooman and Chica. They sang a song to the tune of "Turkey and the Straw" about New Year’s resolutions - Grover's included discovering a new breed of blue apple, tying his shoes, dancing with a penguin, and eating hot chocolate with a dove. He thanked his family when he was given the "Super" Good Egg Award.
• Elmo (Kevin Clash, who played him until 2012) appeared on December 15, 2009 with Sean Roach and Chica, where he answered viewers' phone calls, read birthday cards, played in a color game show and sang songs such as "Blue Kazoo Blues" and "Kwanzaa Candles." The character returned on November 30, 2010 for Food and Cooking Week with Kelly Vrooman and Chica, and again on Christmas Eve that year. He once again returned on December 13, 2011 with Liz Filios and Chica, where a dreidel hit his puppeteer. The character returned in 2016 with Cookie Monster to promote their new show The Furchester Hotel.
• Abby Cadabby (Leslie Carrara-Rudolph) appeared on January 4, 2012 for Weather Week with Liz Filios and Chica.

Now for Barney.

• The big purple dinosaur himself appeared for Thanksgiving 2007 with The Good Night Show's Nina (Michele Lepe) and Chica, and later that day he hosted a marathon of his show where he presented hand turkeys from Sprout characters. The character returned for Valentine's Day in 2009 with Sean Roach and Chica, Dinosaurs Week in August 2010 with Kelly Vrooman and Chica, Valentine's Day 2011 with Roach and Chica, and Thanksgiving 2011 with Liz Filios and Chica.
• Riff (Michaela Dietz (who also voiced Amethyst from Steven Universe)) appeared for Friends Week on March 31, 2011 with Liz Filios and Chica to promote Season 10 episodes of the show coming to Sprout.

The Wiggles also appeared, but I'm not counting them since they're performers with a children's show and direct-to-videos, not a fictional world.

Now for LazyTown.

• Sportacus (Magnus Scheving, the creator of the show) appeared for Good Sports Week on July 27th, 2012 with Sean Roach and Chica.
• Stephanie (Chloe Lang) appeared in 2012 with Kelly Vrooman and Chica. They sang "Head, Shoulders, Knees, and Toes" and made a healthy pizza.

Zack from Zerby Derby appeared in 2014 with Tim Kubart and Chica, and again in 2015 with Carly Ciarrocchi and Chica.

Noodle from Noodle and Doodle appeared to promote the show in 2010 with Sean Roach (who hosted the show) and Chica, again the same year with Liz Filios and Chica. She was also present at a pajama party with Filios and Chica the same year. 

Mr. and Mrs. C from The Chica Show appeared several times - once together to promote the show in 2012 with Sean Roach and Chica. Mr. C often appeared for Father’s Day, and Mrs. C made appearances before The Chica Show even began, albeit with a yellow necklace.

Now for Pajanimals.

• Squacky appeared for Fall Week 2011 with Kelly Vrooman and Chica, and again in 2012 with Dennisha Pratt and Chica.
• Sweetpea Sue appeared for Valentine's Day 2013 and helped Sean Roach and Chica make Valentine's Day cards.
• Granny Pearl appeared for Grandparents' Day 2012.

Now for the blocks.

• Nina (Michele Lepe) from The Good Night Show has guest hosted several times, probably a lot more before they hired Sean Roach (who I’m friends with on Facebook). A few instances were Thanksgiving 2007 with Barney (see above), New Adventures Week on September 21st, 2009 (to promote her fifth season), and for Scrambled April Fun Day 2011, where she and Star played a Sink and Float Game with Kelly Vrooman and Chica. Star himself also appeared multiple times - once for Space Week 2010 with Kelly Vrooman and Chica, and at a pajama party the same year with Liz Filios and Chica.
• The characters from The Sprout Sharing Show appeared in 2008 and again in 2010 with Dennisha Pratt and Chica. Patty appeared alongside Elmo in 2010, and at a pajama party with Liz Filios and Chica. Curtis E. Owl and Otis appeared in 2012 for Chica's birthday party.
• Miles (Milton Barnes) from The Let's Go Show appeared for New Year's Eve 2007 and Day 2008.
• Bean from The Super Sproutlet Show appeared for Valentine's Day 2012 with Liz Filios and Chica, which was also the day the block premiered (SURPRISE!)
• Meeka and M'Goats from Sprout Control Room appeared in 2014 to promote the premiere of Astroblast!.

Animated characters also appeared, but rarely. From what I have heard, Super WHY! appeared in 2011 to promote his show with Liz Filios and Chica, and the titular characters from Ruff-Ruff, Tweet, and Dave appeared to promote their show in 2015 with Emily Borromeo and Chica.