The Bakers
- Cool Big Sis: Everyone sees her as this.
- Happily Married: To Bud in the sequel.
- Love Makes You Dumb: She ignores all the warning signs that Hank isn't the guy for her, in part because of love and in part because she needs him to assert her independence from her family. Fortunately, she later dumps him.
- Only Sane Woman: She is this to her family.
- Aloof Big Brother: Becomes this after the family moves because he's miserable at his new high school.
- Break the Cutie: Rare example for a male character. Charlie starts out as a good-natured and friendly kid who gets transported to a new city and goes to a school where he's actively singled out for bullying. He remains relatively stoic throughout most of the harassment, but the corn-in-the-locker prank appears to be his breaking point as he can be seen tearing up like he's trying not to start crying.
- Red Is Heroic: Wears a bright red Midland baseball cap in most of his scenes - and insists on wearing it even after being told not to when he moves to Evanston.
- Hypocrite: Laughs at Hank after the dog starts chewing out his junk as part of his siblings' prank (and doesn't express any disapproval of it later), but is extremely sensitive to even light teasing from his teammates, never mind the full-on prank that comes later.
- Cool Big Bro: Is this initially, especially to Henry.
Mike Baker (Blake Woodruff)
Nigel & Kyle Baker (Brent and Shane Kinsman)
First Movie Supporting Characters
The Shenks
Played by Steven Anthony Lawerence (Dylan), Paula Marshall (Tina) and Alan Ruck (Bill)
- Adaptational Jerkass: Tina, who is over-protective of Dylan and is not fond of him playing with the Bakers, the main characters of the film. She initially started out as the Bakers' new next-door neighbors, but soon she became a more prominent character. As she, her husband and son are approaching the new Baker house, she notices cartons and cups on the dashboard of the Baker van and looks down on them rudely calling them fast food people. She was rather surprised that the Bakers had twelve kids, and was appalled when Dylan played hockey with them indoors. Tina thinks that the Baker kids will end up on milk cartons and even makes Dylan's birthday party fancy instead of normal (despite having a bouncy castle for the kids). After Dylan is landed in the hospital after the Baker kids ruin his birthday party while they snuck out of the house being grounded and Tom Baker falls on him, Tina furiously tells him his kids can no longer play with Dylan and angrily rants about them. So there you have it folks, particularly ever since the birthday incident, and even before that, Tina starts to form and develop hatred towards the Bakers.
- Henpecked Husband: Bill doesn't offer much resistance to Tina's usually domineering style of parenting, and it is subtly implied that he would've happily had more children if Tina had willed it. It's when one of the Baker children go missing though that he ignores Tina and offers whatever help he can.
- Insult Backfire: When Mark, one of the Baker kids, runs away, Tina rudely says that she knew "One of their kids would fall on a milk carton." And says that 12 is too big a number. She then says that they'll never find him and to let the police handle it, but Kate replies that they will, because "Like you said, 12's a big number."
- Lonely Rich Kid: Dylan's family is very well off and his parents throw him a ridiculously lavish birthday party instead of a normal one with party hats, cake, or even a clown. He loves the company of the Baker kids and wants to have siblings, but his mother won't let him.
- Nice Guy: Bill is nice, having a much more open mind towards the Bakers than Tina. When she straight up refuses to help the family find Mark, Bill and Dylan immediately volunteer regardless of Tina's protests.
- Siblings Wanted: Dylan desperately wants to have siblings, but his mother refuses to have any more.
Second Movie Characters
Sarina Murtaugh (Carmen Electra)
- Hidden Depths: She is initially presented as Jimmy's Dumb Blonde trophy wife, but she truly wants to be a good mother to her stepkids. When she sees the wedge that Jimmy's pressuring and obsession with upping Tom is driving between himself and his kids, she sets him straight.
