Played by Jon-Erik Hexum
- Book Dumb: Bogg never paid proper attention in class due to being distracted by Susan, an attractive female classmate. As a result, he doesn't know a lot book-wise.
- Brilliant, but Lazy: In "The Trial of Phineas Bogg", Susan tells Bogg that he could have done much better if he'd actually applied himself. "All Fall Down" further supports this interpretation when Bogg reels off a bunch of historical facts about Joe Louis; when Jeff expresses surprise, Bogg simply says that this kind of history is interesting to him.
- Doesn't Like Guns: Bogg doesn't like guns, seemingly because of how easily they can kill people. It becomes a major plot point in "Bully and Billy" when it causes a major disagreement between him and Jeff.
- Embarrassing Last Name: He seems to view it that way. In "Merry Christmas, Bogg", when Jeffrey originally points out Gompers, Bogg thinks he's just remarking on what a horrible last name he has and says Gompers can deal with his last name if Bogg can deal with his.
- Identity Impersonator: Sometimes his job requires taking on the persona of another individual. During "An Arrow Pointing East", he poses as Robin Hood and in one episode he tells Jeff that he did some of Nijinsky's dancing for him.
- Last-Name Basis: Jeffrey always refers to Bogg by his surname, never as Phineas (or anything else), which gets pretty odd during highly emotional moments.
- Resentful Guardian: Bogg fills this role initially; he had never intended to have a kid along with him while he's time-traveling and trying to flirt with the ladies. Once he realizes how traumatized Jeffrey is, he lightens up.
- The Teetotaler: During one early episode, he says that he doesn't drink.
- Why Did It Have to Be Snakes?: While it doesn't really get in the way, the series hints multiple times that he doesn't like and may be afraid of dogs.
Played by Meeno Peluce
- Alliterative Name: His first and last name both begin with J.
- Brainy Brunette: Jeffrey is quite resourceful and knowledgeable and has brown hair.
- Curtains Match The Windows: His hair and his eyes are both dark brown.
- Heartwarming Orphan: Jeff, an orphan at the beginning of the series, tends to be liked by most of the people he encounters. One of the bigger examples is his effect on Bogg, who transforms from self-proclaimed loner to protective caretaker after getting stuck with him.
- Heroes Love Dogs: He owned one, Ralph, before the story began.
- Like a Son to Me: After a little while of time-traveling together, Bogg comes to see Jeff as being like his son (he actually says to another character that Jeff isn't his son, but he wishes he could say he was). While they don't quite have an average father/son relationship, he does try to teach and protect him.
- Mouthy Kid: While generally good-natured, he is not above snarking at Bogg when he does something unwise.
- Not So Above It All: While he's often the one who has to keep Bogg on task, there are times (such as "Bully and Billy") when he does unwise things and Bogg has to keep him in line.
- Parental Abandonment: Jeffrey's parents died in a car accident before the beginning of the show (and his aunt, who was boarding him, wasn't too keen on having him there; consequently, he latched on fiercely when the time-traveling Phineas Bogg showed up in his life, having nothing in particular to leave behind.
Bill and Kathy Jones
- Deceased Parents Are the Best: They were killed before the beginning of the story. However, they and Jeff seem to have been very close in life and he never has anything but fond memories of them.
- Posthumous Character: They died in a car crash/conflagration before the first episode.
Played by Jenny Neuman
- Chekhov's Gunman: A long-term example possibly crossing over with Brick Joke; Voyager Susan turns out to be the mysterious blonde classmate who distracted Bogg during his time at the academy.
- Crusading Lawyer: While in the episode where she appears, she has been assigned to Bogg's case rather than taking it voluntarily, she makes it clear she thinks Drake is up to no good and wishes she could find the evidence to prove it. When Bogg brings up Drake's "diary" of underhanded deeds that he kept during his academy years, she's the one who actually enters Drake's quarters to find it and reveal his true nature.
- Everyone Loves Blondes: She's blonde, and Bogg certainly finds her attractive.
- Nice Girl: She's quite personable.
- Ship Tease: Bogg's been interested in her since the Voyager academy, and when Jeff accidentally reveals this to her, she says Bogg should have let her know so that she could have acted on it.
Played by Stephen Liska
- Arch-Enemy: While the series didn't continue long enough for it to be a major theme, he serves as Bogg and Jeff's nemesis, being the only foe they've fought more than once and making it personal both times.
- Beethoven Was an Alien Spy: Subverted in "Jack's Back". Jeff asks if Jack the Ripper was really Drake. Bogg says it isn't like him and thinks he's just trying to mess up history by going after Nellie Bly.
- Karma Houdini: Thanks to the series getting cancelled, he never gets caught — though the fact that he failed to frame Bogg (who he hates) not once but twice probably needles him.
- Recurring Character: He appears as the antagonist in "The Trial of Phineas Bogg" and again in "Jack's Back".
- Small Role, Big Impact: He only appears in two episodes, but has probably had more impact on Bogg and Jeff's lives than any other antagonist they've faced.