Guess with Jess is a British and Canadian interactive animated television series featuring Jess the Cat from the TV series Postman Pat. It follows Jess's adventures with his friends on Greendale Farm, and how they always try to solve each other's problems with a Big Question, which is answered by "asking, testing, find a way". The series is an enquiry-based learning show aimed at two to four year olds. Jess and his friends search for the answers to science and nature-led questions, allowing children to learn about the world around them.
- Jess – a black and white cat, from the BBC series Postman Pat. He is also the protagonist.
- Willow – a brown and white pony wearing a sunhat. The largest of all the characters, she acts as a wise mother figure to Jess. Willow shares the stable with the puppies, Joey and Jinx.
- Mimi – a pink and white rabbit. She lives in her hutch and enjoys all things arts and crafts.
- Baa – a sheep with a blue wooly hat and a blue and white scarf. He always hangs out with Billie, who both live up in buttercup meadow. Baa tends to be afraid of more things than the others and particularly hates getting wet because the water stays in his wool a long time, making him cold and miserable and also makes his wool heavy.
- Billie – a fieldmouse. She is often seen with Baa and rides around on his hat, since Baa can get places faster than she can. She carries a magnifying glass and a set of binoculars so she can investigate the "big question" further.
- Horace – a frog who wears large glasses and lives at the pond. He loves making music and instruments out of natural found objects.
- Joey and Jinx – two twin brother and sister puppies. Joey (the boy) wears a blue collar with a bone shaped dog tag and Jinx (Joey's sister) wears a pink collar with a flower shaped dog tag and a flower in her hair. They both love to run about the farm, rolling about in the mud and jumping over puddles.
- A host of minor characters - such as Sammy Snail, Birdie Bird, Kevin the fish, etc.