Parker played by Jim.
Parker is Lady Penelope's butler and chauffeur.
Jim is a rather gung-ho roleplayer, interested in action, cool fight scenes, and lucrative spoils over careful consideration or puzzle solving. He frequently acts before he thinks, which includes fixating on his own strange explanations for setting details that the GM hasn't explained yet.
Lady Penelope played by Ben.
Lady Penelope Creighton-Ward is an English upper class socialite and fashion model.
Ben is a thoughtful roleplayer who tries to think through the best course of action within his character concept and the setting. He enjoys coming up with clever ways to justify the success of his plans within the premises of the setting.
Virgil played by Pete.
Virgil is the third Tracy son.
Pete is an old friend of Jim's. Jim invited him along to join in this new game. Pete designed a character to maximise all the skills he thought would come in most useful in a rescue campaign, at the cost of having That Weird Name People Always Snicker About, Sensitive New Age Pianist Guy, and Highly Strung.
Brains played by Sally.
Brains is the scientist and inventor behind the Thunderbirds machines.
Sally is somewhat younger than the other players, but has grown to be an integral part of their gaming group. She has an active imagination and enjoys inventing details about the game setting and characters. Her gaming style is maturing as she grows older.
Jeff played by Annie.
Jeff is the patriarch of the Tracy family and leader of International Rescue.
Annie was interested to come along and see what this "roleplaying games" thing was all about, hearing it was a sort of improvisational acting thing. She is dedicated to playing her character as a real, complex person with motivations inspired by a well-considered backstory.
Alan played by Corey.
Alan is the fifth and youngest Tracy son.
Corey is Pete's nephew and was keen to play the "cool roleplaying game" that Pete told him about. He is relatively new to the world of tabletop RPG gaming but has adapted quickly to playing a character and thinking as they would.
Scott is the oldest Tracy son. He uses his great wisdom and popularity to act as field commander for International Rescue. How exactly he gets away with this is a mystery.
Gordon is the fourth Tracy son. His main concern is finding more ways to use the Lost Thunderbird of Phanastacoria in non-aquatic rescue missions.
Kyrano is the Tracy family's manservant. Jeff trusts him, but Alan is suspicious of him because... Just because. Who is right remains to be seen.
Tin-Tin is Kyrano's daughter. She keeps an eye on the Tracy boys and tries to keep everyone out of trouble, which seems to be a very difficult thing to do with them racing off to meddle in perilous situations all the time.