From the world of Milo Murphy's Law…
Milo Danger Murphy - The fourth great-grandson of Murphy's Law namesake Edward A. Murphy Jr. He always expects the unexpected, considers life an adventure, and makes the best of everything whenever anything that can go wrong usually will.
Melissa Chase - Milo and Zach's best friend and the first person brave enough to befriend the former. She tends to lose her personal belongings and feared rollercoasters after one nearly fell on her.
Zach Underwood - The new kid in town and former main vocalist of the Lumberzacks. He tries to enjoy being Milo's best friend and serves as the voice of reason when things go out of hand.
Diogee Ex Machina Murphy - The Murphy family's dog. He always follows Milo, usually helping him out whenever he's in trouble.
Balthazar Cavendish - One half of a couple time traveling pistachio vendors. He tends to be the more serious of the duo.
Vinnie Dakota - The other half of a couple pistachio selling men and time travelers. He's more laidback and lazy than his partner.
Sara Murphy - Milo's older sister and a big Doctor Zone fan. She is protective of her younger brother and likes spending time with him.
Martin and Brigette Murphy - The parents of Milo and Sara, who work as a city safety inspector and architect, respectively.
Cavenpuss - A human-platypus hybrid created by Dr. Doofenshmirtz, combining DNA from Cavendish and Agent P.
From the world of Phineas and Ferb…
Heinz Doofenshmirtz - An ex-evil scientist who is destined to invent time travel and the former enemy turned friend of Perry the Platypus. Due to the Murphy's Law collapse of his company Doofenshmirtz Evil Inc. in The Phineas and Ferb Effect, he becomes a houseguest at the Murphy's and a series regular since then.
Perry the Platypus (Agent P) - The Flynn-Fletcher family's pet platypus and Doofenshmirtz's former enemy turned friend. He is the best agent at OWCA (Organization Without a Cool Acronym).
Vanessa Doofenshmirtz - Heinz and Charlene Doofenshmirtz's goth and sarcastic teenage daughter from their failed marriage.
From the world of PAW Patrol…
Marshall - A clumsy, funny, and excitable yet trustworthy Dalmatian who serves as the team's competent firefighter and medic pup. Almost always crashing into the Lookout's elevator – in which he always wants to get in first before the others – and stuff in the way, he isn't very good at keeping secrets and loves making countless puns.
Everest - A hyperactive and reliable lavender Siberian husky introduced in Season 2's The New Pup. Initially having no one else to talk to, she resides at Jake's Snowboarding Resort and lives the best life a husky could ask for. She loves nature, liver, and pizza and is the first pup to join the team as their snow specialist and second female.