The host of the show, who knows historical dates down to the second and wear watches from his shoulder to his wrist. Voiced by Frank Welker.
- Cool Old Guy: He brings several children along with him through the past to educate them about history.
- Mad Libs Catch Phrase: The above quote. Sometimes he switches it and says "the place..." first.
- Mister Exposition: He explains everything about the eras of history he and the other characters visit.
- No Celebrities Were Harmed: In some sketches, he plays characters as imitations of Bill Cosby.
Big Fat Baby
Father Time's sidekick, and the reason why Histeria! was considered a Gross-Out Show (yet Lydia Karaoke doesn't call the show out on it). He is an egg-shaped parody of Baby New Year with a nasty habit of crapping his diaper. Voiced by Luke Ruegger (brother of Nathan and Cody Ruegger; son of Tom Ruegger)
- Bring My Brown Pants: Regularly craps his diaper.
- Cephalothorax: Comes off as this due to being egg-shaped and having no neck.
- Fartillery: The Kid Chorus uses him as this in "Big Fat Baby Theatre".
- Infant Immortality: Seriously, look at what he can survive in The History of Poland sketch.
- Running Gag: The kids request help changing Big Fat Baby's diaper, claiming the last time he had a clean diaper was before something that happened a long time ago.
A ditzy but attractive tour guide who sometimes makes mistakes with the information she gives out. Voiced by Laraine Newman.
- Brainless Beauty: She's quite a looker, but not very bright.
- Catchphrase: (to tour group) "Stay together, people. We're walkin'... we're walkin'..."
- Meaningful Name: True to her name, she's mistaken about certain things and has to be corrected by other characters.
- Punny Name: Her name is a play on misinformation.
World's Oldest Woman
- Abhorrent Admirer: As Cleopatra (and herself occasionally)
- Dirty Old Woman: Hits on Bill Straitman whenever he interviews her and has dated every male world leader in history
- Everyone Calls Him "Barkeep": She's only ever known as the World's Oldest Woman.
- Fan Disservice: Her portrayals of Lady Godiva and Cleopatra in "A Tribute to Tyrants". The former actually follows the famous legend of Lady Godiva protesting against her husband Leofric's tax by riding horseback in the nude, while the latter has two occasions where she's in the tub and wants her back to be scrubbed by either Julius Caesar or Mark Antony.
- Really 700 Years Old: She looks like your normal senior citizen, but is actually as old as time itself (she claims to have dated every man in history, starting with Adam in the Garden of Eden).
A mischievous brown-haired boy who likes to make his statements clear by shouting them in the loudest volume possible. Voiced by Cody Ruegger (brother of Nathan and Luke Ruegger; son of Tom Ruegger)
- Animated Actors: The episode "The Teddy Roosevelt Show" reveals he is also a writer for the show.
- Brats with Slingshots: He is shown using a slingshot in "Histeria! Goes to the Moon".
- Catchphrase: Often yells "What a grouch!" whenever someone is being extremely rude to him.
- Honest John's Dealership: One episode was about him running dealerships of various historical things, like vacations in Pompeii.
- Ink-Suit Actor: Based on his voice actor, Cody Ruegger, who according to his dad Tom, "tended to be the loudest kid on Earth".
- Karmic Trickster
- Meaningful Name: As his first name would suggest, he constantly shouts his dialogue.
- No Indoor Voice: Loud is, to quote the main page for this show, "more like 'Halfway across Manhattan Voice'".
- Running Gag: He likes to keep watch of things, silently muttering "See it, see it..." when it's visible and screaming "DON'T SEE IT!! DON'T SEE IT!!" when it disappears.
- Tagalong Kid: To the Super Writers.
- Volumetric Mouth: He talks like this.
A short blond kid so named for his deep, frog-like voice. Voiced by Nathan Ruegger (brother of Cody and Luke Ruegger; son of Tom Ruegger)
- Big Eater
- Gadgeteer Genius
- Innocent Prodigy: He's very intelligent, but just as immature as the other children.
- Large Ham: When the Wright Brothers can't provide him with the tools he needs, his displeasure is over-the-top and melodramatic.
- Meaningful Name: His voice sounds like a frog croaking.
- Only One Name: He has no surname.
- Picky Eater: "A turnip? Yick! Now I'm really sick!"
- Vocal Dissonance: He's a preteen kid with a voice that sounds like it should belong to a bullfrog the size of an ox.
A melancholy blonde girl who almost always seem to be in a glum mood (except when singing). Voiced by Laraine Newman
- Catchphrase: "I'm not happy".
- The Eeyore: She's always melancholic.
- Friend to All Living Things: Seen in "When America Was Young".
- Hair Decorations: Wears a bow and a headband.
- Little Miss Snarker
- Punny Name: A play on "charity bazaar".
- Punny Name: Her name is a play on a capella, a term referring to a song sung without the addition of musical instruments.
- Sassy Black Woman: A downplayed version of the typical examples.
- Catchphrase: "Ripoffski!" and "Gypola!" (which she sometimes says after getting autographs). She also says "Yuckosis!" when she sees someone doing something disgusting.
- Cloudcuckoolander: Can't get any nuttier if she confuses every historical figure she encounters with pop culture figures.
- Genki Girl: She's downright excitable most of the time.
- Hidden Depths: In spite of her tendency to mistake the historical figures she demands autographs from for famous pop culture icons, she is occasionally shown to know her facts about history and there are some episodes where she excitedly states her admiration towards a historical figure that she isn't mistaking for someone else.
- Historical Character Confusion: Has a habit of asking historical characters for their autograph, then realizing that she had mistaken them for someone else.
- I'm Your Biggest Fan: She wants the autograph of every historical figure she meets, though she always has no idea who they really are.
- Loony Fan: Asks historical figures of their autographs and gets furious when she realizes too late that she's mistaken them for someone else.
- Mad Libs Catch Phrase: "Heeey, you're not ___!" or "Wait a minute, you're not ___!"
- Running Gag: She constantly asks historical celebrities for their autographs, only to find out they're not the pop cultural celebrity she mistook them for.
- Squee!: She often ends her sentences with a loud, high-pitched squeal when she's excited.
A sunburned teenager who never seems to have a clue about what's going on around him, and never has any interest in the things his guest stars talk about. Voiced by Tress MacNeille.
- Cloudcuckoolander: He thinks that everything important has to revolve around surfing or rock music.
- Only One Name: He's only ever referred to as "Toast", and for that matter we're not even sure if Toast is his real name.
- Totally Radical: He appears to be an Expy of Bill & Ted (fittingly enough).
An obsessive Asian salesgirl who refuses to leave her customers alone until they have bought something from her. She is almost always accompanied by Lucky Bob. Voiced by Tress MacNeille.
- Leitmotif: "Chopsticks" can always be heard as background music whenever she speaks.
Cho-Cho's slow-witted sidekick who likes quoting Ed McMahon. The"Underground Railroad" sketch on the episode "General Sherman's Campsite" explains that Lucky Bob was once kicked in the head by wild donkeys (and is called "Lucky Bob" because that only happened to him once), which would explain why he's such a drooling pinhead. Voiced by Jeff Bennett.
- The Ditz: He's a complete dunce.
- Dumb Blonde: Gender-flipped, as he's a boy rather than a girl like the trope usually is.
- No Celebrities Were Harmed: A lot of his mannerisms were based on the late Ed McMahon.
- Big Eater: One sketch in "Heroes of Truth and Justice" had him sick from eating too much hot dog soup.
- Butt-Monkey: He gets hurt for comedic effect in just about every one of his appearances.
The smartest man in the world, but also so incredibly shy that he wears really tall pants with which to partially cover his face. Voiced by Rob Paulsen.
- Getting Crap Past the Radar: He finds it hilarious when this happens and Lydia Karaoke has accused his segment, "What I Find Inside My Pants", of doing this.
- Hammer Space: He can apparently store anything inside his pants.
- Heh Heh, You Said "X": He often laughs whenever he says something that sounds inappropriate. One example is in "Inventors Hall of Fame, Part 1", where he chuckles every time Thomas Crapper's name is mentioned.
- Meaningful Name: "Smartypants" is a synonym for "know-it-all" and most of his body is covered by his pants.
- The Smart Guy: He is said to be the smartest guy in the world.
- Non-Human Sidekick: To Loud.
- Shout-Out: Resembles Hunter from Road Rovers (coincidentally, both this show and Road Rovers were on and off the air for about a year and were made by the same company), albeit a tad darker. Word of God said it was intentional!
- Talking Animal: He occasionally speaks, one instance being in "The Know-It-Alls" when he asks Rene Descartes to play fetch with him.
An egotistical salesman with some sanity issues. Voiced by Billy West.
- Honest John's Dealership: He often appears offering his services to historical figures, only to inconvenience them.
- No Celebrities Were Harmed: He is a parody of Phil Silvers' Sergeant Bilko character.
- Slasher Smile: He is constantly grinning.
- Small Name, Big Ego: Is completely unaware of how shoddy his services are.
As his name implies, he is the straight foil to the other comedic characters. Can often be seen interviewing The World's Oldest Woman about the many historical events and people she's seen/been with. Voiced by James Wickline.
- Meaningful Name: He is the straight man to the other characters.
- No Celebrities Were Harmed: Based on Carl Reiner, specifically his role with Mel Brooks in their "2,000 Year Old Man" routine.
A smarmy network executive. Voiced by Rob Paulsen.
- Small Name, Big Ego: He's frequently under the delusion that his ideas are better than everyone else's.
The resident network censor who sometimes objects to whatever antics the rest of the cast gets up to. Voiced by Nora Dunn.
- Designated Villain: She's pretty much the closest thing to a recurring antagonist, though there are times where she is seen in the sketches, often in crowd scenes or as a game show host.
- Butt-Monkey: Sometimes, she gets the worst treatment out of all the characters (particularly when she gets blasted by torpedos and discovers the real reason why "Damn the torpedoes" is an appropriate phrase, despite containing a word that's considered taboo on American children's TV). The treatment is justified as, in most of Steven Spielberg's cartoons, network censors (along with studio executives and lawyers) are Acceptable Targets to mock and make into villains and ButtMonkeys.
- Executive Meddling : Whenever she interrupts a sketch over risque/gross/violent content. One episode had her interrupt Billy the Kid's kid show to complain that he's a violent criminal and his line asking the kids to get a six-shooter from yonder barn will lead to copycat incidents, then tells him that his kids' show can be salvaged if they make it appealing to the young female demographic, so she (briefly) turns him into a cowgirl.
- Media Watchdog, Moral Guardian, Political Correctness Gone Mad: Her character and appearance on the show represents how network TV cartoons back in the mid-to-late 1990s were being subjected to censorship and Executive Meddling (and her comic abuse is basically the creators taking potshots at the powers that be).
- Think of the Censors: Inverted; the main cast doesn't care if what they say or do is risqué, but Lydia does.
- Well-Intentioned Extremist: She doesn't care if her actions interfere with historical accuracy or otherwise prevent the show from being entertaining. She will not tolerate any material that people would find inappropriate to include on a children's show.
- Leitmotif: Always accompanied by Brahms's "Symphony No. 1 - Movement 4".
- Mad Libs Catch Phrase: Her segments often ended with her saying "And may all your X be Y!"
- Overly Long Name: Just look at her last name!
- No Celebrities Were Harmed: Paul Rugg is using his Jerry Lewis-esque director voice from Animaniacs.
- Perfectly Cromulent Word: He frequently says "predictiate" in place of "predict".
- Verbal Tic: He frequently says "Shaddap!" between every other word he says.
Molly Pitcher was a woman who supposedly carried water to cannon crews during the American Revolutionary War. It's said that when her husband, one of the cannon crewmen, was wounded during the Battle of Monmouth, she took his place at the guns. Now, she tends to show up whenever anyone in the series needs or talks about water (It's either her or Montezuma, and you don't want that!). Voiced by Tress MacNeille