Johnny is typically seen as the awkward or odd child in the Cul de Sac. He is innocent and gullible and is generally called a nuisance by the other kids in the Cul de Sac, even so he is still accepted by everyone. He is usually seen with his imaginary friend, Plank. Plan is a 2x4 with drawn on eyes that Johnny will often talk to, yet nobody else can understand what Plank is ever saying.
Johnny has an abnormally large head compared to the other residents in the Cul de Sac, typically being a target for jokes or insults because of this. Johnny has several short hairs atop his head, like most of the male residents in the Cul de Sac. He wears a large white T-Shirt and blue jeans. Johny is also the only kid in the Cul de Sac who is always seen wearing sandals.
Johnny also wears half a watermelon on his head when becoming his 'Captain Melonhead' persona. He also switches out his white T-Shirt for a long sleeved yellow V-neck. Somehow Johnny is able to keep the other half of the watermelon under the first, he does this so that if someone tries to unmask him he'll have another mask to protect his superhero identity.
Johnny also is a member of the Urban Rangers with Rolf and Jimmy and has an Urban Rangers uniform.
Johnny's character was based on that of a loner with an imaginary friend that the shows creator saw around his own neighborhood as a kid. Johnny is awkward and has various odd mannerisms, like Rolf however Johnny isn't from a different country. He has an incredibly active imagination, like Ed, though one might argue that Johnny's is even more extreme. He carries around a 2x4 that he has named Plank, he has also drawn two eyes and a face on the board.
In one episode Johnny and his quirks were analyzed by Edd who explained that his desire to have conversations with inanimate objects is normal, this caught Eddy off guard. Edd also explained that Johnny's behavior could be the direct result of various phobias, one of which being social anxiety or a lack of self confidence. Johnny uses Plank to communicate with others because he lacks social skills. Johnny's lack of social skills is commonly displayed, as most of the other kids in the Cul de Sac find him to be annoying.
Johnny is a rather adventurous child and appears to have more freedom than some of the other kids in the Cul De Sac such as Kevin or Rolf. Johnny has an incredibly open mind, which would explain why he's the most tolerable of the Ed's, he even views their various scams as entertainment. In one instance Johnny joined Jimmy and went on a cruise hosted by the Ed's, it was during this that he displayed a great sense of adventure ( this is due to the fact that he sabotaged the boat being used by the Kanker Sisters ).
Johnny also is one of the more curious members of the Cul de Sac, often asking questions such as "What's that" or "Why" over and over. This habit causes Johnny to easily get on the nerves of the other kids in the Cul de Sac. The Ed's once took advantage of Johnny in one of their scams, using his intolerable annoyance as a tool against the other kids. This plan ended up backfiring when his annoying tendencies failed against Rolf, this is due to the fact that Rolf also has odd social behaviors.
Johnny was also shown to be able to freak out Ed, a surprising feat due to the fact that Ed himself is brain-dead and appears to lack any sense of fear or danger.
Johnny also doesn't acknowledge that nobody else can understand what Plank is saying. He also doesn't grasp the idea of an imaginary friend, though for some reason Plank was able to explain to him what it was.
Though Johnny typically has a "happy go-lucky" attitude towards everything he is susceptible to fits of rage. These fits happen whenever his imaginary friend, Plank, is threatened. Johnny goes into a type of berserk rage that grants him insane levels of strength and durability, it may be possible that Johnny is tied with, or stronger than Ed during these moments.
There was an instance in which Johnny and Plank got into an argument causing Johnny to abandon Plank and put him in Jimmy's care. Edd then tried to help Johny find a new inanimate object friend such as "Bob" who was a traffic cone with a face drawn on. Johnny became visibly sick when Eddy had forgotten to draw an eye on the cone. Johnny also tried to befriend a boot named Salty, though after several moments alone with the boot he began screaming in terror claiming that "Salty's gone mad".
Johnny then went to a social mixer and became afraid of the other inanimate objects, stating that they were all staring at him. Johnny eventually became friends with Plank again at the end of the episode.
Johnny's imagination also has given him a superhero persona known as Captain Melonhead. When Johnny goes into this personality he changes his appearance and wears a Melon on his head. Johnny has a hideout known as the Meloncave that can be found under his house, it is possible that it is a parody of the Bat Cave. Johnny rides around on Planks superhero personality known as 'Splinter the Wonderwood' which is just plank tied to a broom while he wears a mask with eyes drawn on it. Johnny appears to be more serious when he becomes Captain Melonhead, he is very protective of his identity and believes that it is his job to protect the other kids of the Cul de Sac from the dangerous scams created by the Ed's. This is interesting to see because when Johnny is in his normal personality he often falls for the scams he protects others from, this could hint at Johnny having some sort of personality disorder. Johnny once combated Eddy who became a supervillain known as Professor Scam, though this only happened once.
Johnny seems to be a deep sleeper, and was once used as a projectile by Eddy while he was sleeping. Even when thrown around he still doesn't wake up.
Johnny also has his own Supervillain persona known as "The Gord" who he became at the end of the movie Ed, Edd n' Eddy's Big Picture Show, though nothing is known about the Gord since he was only seen at the end of the finale and never actually did anything.
Johnny's strongest ability is probably that of his imagination, typically being able to come up with solutions that the others would have overlooked.
Johnny also has the ability to annoy others to the point that they would pay the Ed's to get rid of him. Rolf is the only one that seems immune to this due to his own odd social habits.
Johnny can become incredibly strong and durable when Plank is in danger, as he would do anything to save Plank.
When Johnny becomes Captain Melonhead he obtains new abilities
- Superhuman Agility - He is easily able to navigate through forests and balance on tree limbs while running. He can also jump higher than normal humans.
- Superhuman Speed - Johnny is able to run faster than anyone else when he is Captain Melonhead
- Automatic Growing Acorns - Probably the most useful and effective abilities that Johnny gains under the Captain Melonhead guise is the Automatic Growing Acorns. When Johnny throws them they turn into a full grown Oak Tree.