|Introduced in||"Memories of Boom Boom Mountain"|
|Latest appearance||“King Worm"|
|Voiced by||Kent Osborne|
Joshua is a dog who is the father of brothers Jake, Finn, and Jermaine. He and his wife Margaret adopted Finn as a baby. He speaks in a 1940s Mid-Atlantic accent. Joshua's personality is demonstrated as an old-fashioned manly dog who is willing to push his sons to fight, particularly when they need to.
Joshua first appeared with his wife in one of Finn's flashbacks in the episode "Memories of Boom Boom Mountain." They find Finn after he has soiled himself causing him to be stuck to a leaf. Finn claims to have cried for a whole day before anyone helped him. They are the second to stop, after a ladybug mum and daughter, and help the seemingly abandoned baby Finn. They take him to what is presumably their house and raise him as their own.
Joshua returns in "Crystals Have Power," where his ghost appears from beyond the grave encouraging Jake to fight back against the Crystal Guardians of the Crystal Dimension after Jake takes a vow of non-violence. Jake became upset when he remembered Joshua telling him that "Jake would hurt everyone." Jake also sees his brother Jermaine in his flashback. It should be noted that Joshua was trying to tell Jake that "Jake would hurt everyone... who is evil. Let me finish next time."
During "Crystals Have Power," Jake says "stupid ghost dad" when talking to himself out of frustration after Joshua says "Come on, punch them Jake. Punch everybody. Why not? Come on, why not!" Also, when Joshua brings Jermaine to see Jake, Jake asks him if he is dead, implying that Joshua is already dead (Jermaine was not dead, he and Jake were just dreaming at the same time).
In "Dad's Dungeon," Joshua makes Finn and Jake (through pre-recorded Holo-message player cartridges) explore a dungeon he made. The dungeon is filled with traps and monsters to toughen up Finn. Joshua puts Jake's family sword at the end of it as incentive to go through its trials.
In "Jake the Dog," Jake states that during his childhood, Joshua enjoyed making pickles and giving them to him. Also, Jake wears Joshua's hat while caring for his own children. It is assumed that he kept it as a memory of him after his disappearance or death.
Joshua is assumed to be deceased. He, as well as his wife Margaret have probably passed away prior to the events of Adventure Time. The cause of death is unknown. In "Dad's Dungeon," the hologram video shows Joshua being attacked by a Giant Monster, this may have happened while Jake was still a baby since the last hologram shows him telling Finn he finished the dungeon. When Jermaine appears in Jake's vision alongside Joshua in "Crystals Have Power", Jake asks Jermaine if he is dead, implying Joshua is dead. In the beginning of "Dad's Dungeon", Joshua says, "If you're hearing this prerecorded message, it means I've passed on, and my spirit sparkles guided you to its secret hiding place," meaning that he is presumably dead.
Although Joshua does not possess stretching abilities like his son Jake, he is still a tough dog who created a reputation for himself in Ooo prior to his death. He may be able to knit, as seen in King Worm. Joshua knows of at least one incantation, used to slough the Demon whose blood is present in the Demon Sword. In Dad's Dungeon, he seems to create "spirit sparkles." It is unknown if this is a unique attribute or if Joshua even created them at all.
- "Memories of Boom Boom Mountain" (flashback)
- "Crystals Have Power"
- "Memory of a Memory" (photograph)
- "Beautopia" (mentioned)
- "Dad's Dungeon"
- "King Worm"
- "Jake the Dog" (mentioned)
- Unlike Jake, he cannot change his size.
- When Susan draws a picture of a Lub Glub, Jake says, "That looks like my father."
- Both he and Margaret speak with 1940s Manhattan accents.
- Joshua's appearance is similar to Jake; however, Jake is a lighter color of yellow.
- Joshua appeared in "King Worm," where he is seen knitting with green yarn.
- Joshua has grandchildren named T.V., Kim Kil Whan, Viola, Jake Jr., and Charlie, who are born in the episode "Jake the Dad."
- Joshua and Margret seem to have contradicting personalities; Margret being over protective and Joshua pushing his kids to fight.