Avery Bullock's labyrinth in "Game Night" is populated with a variety of mostly benign monsters created by Dr. Weitzman. Some of the notable ones are:
Grunklebean
Grunklebean, aka 'The Cool Bean' greets the Smith family as they enter the labyrinth and is curious about the results of the Tampa Bay Lightning hockey game.
After completing the labyrinth, Jeff carries out a stuffed Grunklebean doll while Hayley wears a set of horns similar to his.
When the family returns for Stan a month after he refuses to leave until he can solve the labyrinth on his own, Steve finds that Grunklebean has hung himself, although Werb-Berg comments he could have died of the plague.
When they find they need to fight their way past Professor Lasagna, Hayley asked who put the Grunkle in his beans.
When the Smith family makes their way back to the CIA break room and realize they've escaped the labyrinth, Grunklebean pokes his head out of the trash chute and they're surprised to see he's still alive. He notes that it was just his way of sleeping.
Groban
Groban is Bullock's herald of the labyrinth and personal favorite. His job is primarily to sing of the challenges of the labyrinth as well as the solution needed to finish it.
Abandoned by Bullock, Groban tries to sing his welcome song when the Smith are returned to the beginning by Mrs. Flermite, but Francine smacks him to the ground in mid-flight.
Groban is voiced by Richard Cheese.
Werb-Berg
Werb-Berb the Woobler oversees the first puzzle of the labyrinth, a sliding puzzle although Stan insists on believing that it must be a physical challenge and slams himself into a wall. As the rest of the family precedes to solve the puzzle, Stan manages to break his teeth testing to see if the doorway is made of gingerbread.
When Stan refuses to leave until he can solve the labyrinth on his own, Werb-Berg complains about the condition it is in,noting that he had moved from Hawaii. He dies from merely touching the Riddle Lord's stream when they try to escape.
Werb-Berg is viced by John DiMaggio.
The Riddle Lord
The Riddle Lord oversees the crossing of a stream by making the Smiths answer a riddle. Stan pays no attention to the clues and blurts out a completely wrong answer as Hayley correctly solves the riddle. When Jeff confront him over being a poor loser, Stan runs off into the maze before answering a second riddle to know which path to choose.
After completing the labyrinth, Steve wears a t-shirt with the Riddle Lord on it.
when the family sets out to leave the Labyrinth and allow Stan to lead the way, the Riddle Lord begs them to take him along as he's desperate to try a cronut. He is killed when Professor Lasagna throws Stan at him during a fight to the death.
Herbert
Stan met Herbert while trying to force his way through the maze and later became his roommate/lover when he refused to leave the labyrinth with the family until he can solve it on his own, although Herbert has no problem with Stan staying forever. When Stan is nearly impaled by spikes in a trap, Herbert sacrifices himself to save him.
Professor Lasagna
Professor Lasagna oversees the essay part of the labyrinth. He awards the rest of the Smith family, minus Stan who went his own way, a C- score for writing a lengthy defense of the man in the song "Baby It's Cold Outside" when they were supposed to be doing an essay on the Civil War.
When they try to let Stan lead them out of the labyrinth, Professor lasagna has changed the challenge to a fight to the death. He is defeated and killed when the family ties his necks into knots, strangling him.
Mr. & Mrs. Flermite
When Stan tries to break down a wall, hoping that they're damaged by termites as the family tries to escape the labyrinth, he's corrected by Mr. Flermite but chooses to crush him instead. When they finally reached the end of the labyrinth, Mrs. Flermite, angered over the murder of her husband, sends the entire party back to the start of the labyrinth.
Mrs. Flermite is voiced by Tara Strong.
Numerous other unnamed monsters are seen at times, including several corpses used to aid in the escape across spikes, as well as several other living monsters that make their way out of the CIA break room trash chute. Unlike most of the others in the maze, these seem to have a more nefarious purpose as they carry various weapons.