Mario is the main protagonist as always. Being made of paper like the rest of the people in this story and the realm his surroundings sure make sure he needs to learn abilities or get new friends to help him along the way. He is really silent but manages to converse enough through however he wants. He's a human like any other game.

Vivian used to work as a member of the villainous Three Shadows alongside her sisters, Beldam and Marilyn. She gave up on that and joined Mario and his party to help him on his way to find the Thousand Year Door. She can help Mario hide in the shadows and more.

Goombella is one of Mario's best friends and an aspiring archeologist. She was one of Professor Frankly's students when studying at U Goom. She helps Mario to try to find the Thousand Year Door and Crystal Stars. She helps Mario by reading her book. She's a Goomba so... Yeah.

Koops is a timid Koopa who hails from a town called Petalburg. Koops is depicted as something of a coward when he is first met, but upon meeting Mario, he changes his way and becomes the bravest Koopa to help Mario and his other friends.

Madame Flurrie is a cloud spirit actress; disillusioned with the world, she retired to the secluded Boggly Woods. After the Punies of the Great Tree were in danger she joined Mario's party to help him like the rest.

He is a spunky Baby Yoshi who is found in the Glitz Pit. He follows Mario and his friends around to help as much as he can with all his little might.

Bobbery joined Mario after Mario found him to be Flavo's navigator to help him get to the Crystal Star then stayed with Mario afterwards. He and his ship got wrecked when helping Mario to an island but luckily the landed there on their location anyways and stayed with Mario. He's a Bob-Omb

Ms. Mowz is a great thief... Really great thief. She can sniff out Hidden Items, Coins, Star Pieces, or even Hidden Badges. However it's like playing Hot and Cold when she does this. She constantly flirts with Mario which annoys Madame Flurrie and Goombella (the latter occasionally calls Ms. Mowz and floozy). She's also apart of Mario's party. She's a Little Mouser.