- Jonah and Broderick Wizard make up a team in the search for The 39 Clues. Jonah is an international rap sensation, and an actor in the series Who Wants to be a Gangsta, having even his own action figure and many other products such as pop-up storybooks, and a Pez container with his face on it, even a frozen treat brand. In the first series, Jonah Wizard dislikes Dan and Amy Cahill, only because they were Grace's favorites. Jonah is one of Amy and Dan's best friends after the Clue Hunt ends.
- Phoenix Wizard is Jonah's twelve-year-old cousin. He gets kidnapped by the Vespers in The Medusa Plot. He escapes in Day of Doom.
- Mr. Wizard is Leila Wizard's husband. He never appears in the books.
- Jonah's mother, Cora Wizard, is the leader of the Janus branch, the youngest ever Nobel Prize winner and has made several sculptures and books, one of which she "donated" to Hope Cahill and Arthur Trent when Dan and Amy were very young, which in fact was an attempt to spy on them with a electronic bug planted on the sculpture. Cora Wizard is considered almost as evil as Isabel Kabra in the 39 Clues series. Cora Wizard didn't set the fire the evening Amy and Dan's parents died, but only because Isabel Kabra had beaten her to it.
- Cora Wizard's husband, Broderick Wizard, was not a born Cahill but joined the family by marriage to Cora. Also, around the time they married, he was an excellent guitarist and a rising star in his college days. Because he is not a Janus by blood, however, he sometimes only has limited access to the Janus branch, as seen in the Janus stronghold in Venice. Naturally, this annoys him a bit. He can always be found on his BlackBerry. He was strongly suspected as a Vesper.
- Broderick T. Wizard - Married into Cahill family, suspected Vesper, Cora's husband, Jonah's father, Mr. Wizard's elder brother, Leila's brother-in-law, Phoenix's uncle.
- Cora Wizard - Head of Janus Branch, Broderick's wife, Jonah's mother, Mr. Wizard and Leila's sister-in-law, Phoenix's aunt (Wizard family by marriage)
- Jonah Wizard - Broderick and Cora's son, Mr. Wizard and Leila's nephew, Phoenix's cousin.
- Mr. Wizard - Minor character, Broderick's younger brother, Cora's brother-in-law, Jonah's uncle, Leila's husband, Phoenix's father.
- Leila Wizard - Married into Broderick's family, Broderick and Cora's sister-in-law, Jonah's aunt, Mr. Wizard's wife, Phoenix's mother (Wizard family by law.)
- Phoenix Wizard - Broderick and Cora's nephew, Jonah's cousin, Mr. Wizard and Leila's son. Kidnapped by Vespers in The Medusa Plot.
Jonah is a huge celebrity. He is a rapper, singer, and is an actor in TV shows/movies.
He is so famous that there are even lollipops made of him, which Dan figures out when he is kidnapped and taken to its factory.
He is Janus, and is part of one of the teams that searches for the 39 clues.