Peanuts set the stage for Snoopy to have an enemy who just so happens to be his next-door neighbor. Going by the names Cat Next Door and World War II, the Cat has major beef with Snoopy, and the feeling is very mutual. They argue constantly, with Snoopy frequently antagonizing the Cat Next Door. Meanwhile, World War II always gets Snoopy back twice as hard for his antagonism, being quite the formidable opponent.

As much as Snoopy tries to act like Mr. Tough Guy, he is actually pretty terrified of the Cat Next Door, quaking in his boots whenever it is time to fight the Cat Next Door face to face. The one exception is whenever Snoopy thinks his best buddy Woodstock is in trouble with the Cat Next Door, and Snoopy swings into action without even thinking twice about it.

13 "A Set of Butter Knives"

August 13th, 1977

Acting as a watchdog for Peppermint Patty, Snoopy meets the love of his life and gets engaged to a beagle, making wedding invitations and going the full nine yards in true Peanuts fashion. He even tries to get a marriage license before he is told that dogs do not need marriage licenses. Ready to receive some gifts for his nuptials, Snoopy reaches out to an unlikely wedding guest.

The Cat Next Door gives Snoopy his gift, but it's not a good one.

Snoopy calls out to his loathed cat neighbor to ask him what he is going to get him and his bride for their wedding present. The Cat Next Door gives Snoopy his gift, but it's not a good one. In fact, the gift is quite painful for Snoopy, who would have preferred to have received a set of butter knives instead.

12 "I'll Kick You with My Cast"

March 6th, 1976

When in his Peanuts strips for many weeks. In one strip from the time when his foot was broken, Snoopy calls out to the Cat Next Door to threaten that if the cat comes near him, he'll kick him with his bulky leg cast. Asking the Cat what he thinks of that, the Cat Next Door answers Snoopy by shredding up his leg cast. While Snoopy is not successful in bonking the Cat with his foot cast, he does hit Linus and Lucy.

11 "The Cedar Closet"

February 22nd, 1969

Ruminating on his hatred of the Cat Next Door, Snoopy its that he knows just how to get under the Cat's skin too. Enacting one such way, Snoopy sticks his tongue out at the Cat but gets scared off by the Cat's anger, hiding inside his doghouse. Comfortable with the new feeling of safety from the Cat, Snoopy feels good about his hiding spot in the cedar closet of his doghouse.

This strip marks the rare occasion that we actually see Snoopy inside his doghouse instead of just on top of it. Snoopy actually avoids going into his doghouse because he gets claustrophobic, so the fact that he hid inside his doghouse shows how scared he was of the Cat Next Door.

10 "I Still Have My Water Dish"

August 23rd, 1981

Questioning if he should antagonize the Cat Next Door, Snoopy eventually decides that he must, so he brags about his supper dish to his enemy. The Cat Next Door responds to Snoopy's bragging by slashing his supper dish in half. Snoopy, not one to let anyone get him down, then focuses on his water dish, grateful that he still has it in one piece. Unfortunately for Snoopy, he should have kept quiet, because the Cat Next Door takes the opportunity to claw a bunch of holes into Snoopy's water dish. Snoopy does not know how to leave well enough alone, especially when it comes to the Cat Next Door, as this strip can attest.

9 "It's Hero Time!"

October 23rd, 1976

Acting as Peppermint Patty's attorney, Snoopy helps her straighten out the confusion about Peppermint Patty graduating... from obedience school, which is unbeknownst to her, as she thought it was her graduation from regular school. When she eventually finds out that the school Snoopy suggested to her in the first place was an obedience school for dogs, she is furious and wants to fight him.

This Peanuts strip includes a rare occasion where Peppermint Patty is just called "Patty."

She sees the Cat Next Door, named World War II, and thinks that he is Snoopy dressed in a cat suit, so she goes over to fight who she thinks is Snoopy. When Snoopy sees Peppermint Patty losing the fight, Snoopy jumps into the fight to help her out, since it's his fault that she's in this mess.

8 "Punch 'Im Out"

August 26th, 1975

Telling Spike that he can take the Cat Next Door in a fight thanks to his years of living out in the desert with coyotes, Snoopy gives his brother a Rocky-level pep talk so that his brother is hyped to punch out his nemesis next door. Someone gets punched, but it is not the Cat Next Door. Instead, the reader sees a massive chunk taken out of Snoopy's doghouse with Spike and Snoopy left standing on the tiny sliver of roof that remains, huddled together in fear. Spending his years out with the coyotes has not done much to make Spike a fighter, especially when his opponent is the fearsome Cat Next Door.

7 "You're Gonna Get Zapped"

April 3rd, 1977

Armed with some home protection equipment, Snoopy taunts the Cat Next Door with his new electric cane and promises to zap him if he comes near. Sick of the Cat Next Door ruining his doghouse, Snoopy threatens that the next time he tries to rip up his house, he is going to zap him. Advising the Cat Next Door to stay in his own yard, Snoopy thinks the attacks are finally finished. To Snoopy's surprise, he is the one who ends up getting zapped, albeit unintentionally, by his own best friend, Woodstock. Snoopy's misfortune is to the Cat's great humor, with Snoopy hearing the Cat belly laugh, perhaps for the first time in Peanuts history.

6 "Flowers"

April 18th, 1978

Snoopy yells to his loathed next-door neighbor about what a nice rain they had the night previously. Snoopy informs the Cat Next Door about how the rain is actually very good for the flowers, but then throws in an insult that a "clod" like the Cat would not know anything about something as pretty as flowers. The Cat Next Door does not take the insult lying down and slashes up Snoopy's doghouse.

However, this does not occur without a little bit of irony first, as seen by the clawed-in flower design the Cat has done on Snoopy's doghouse roof. The Cat Next Door definitely shows Snoopy that he knows all about flowers, which Snoopy will not forget until he gets a new doghouse roof.

5 "He Would Have Been Perfect for the Lead"

September 10th, 1976

Reading in the paper that a remake of King Kong is being made, Snoopy teases that it is too bad that the Cat Next Door did not know about the remake, because he could have played the lead of the classic gigantic gorilla. Insulted to the point of enacting violence - as he tends to do - the Cat Next Door claws at Snoopy and his doghouse, ruining the roof and making Snoopy fall inside.

Little does the Cat know that he actually proved Snoopy's point right, because he just showed that he was perfect for the lead role by destroying Snoopy's doghouse, which is very much like King Kong. Snoopy would have liked to have been proven right in a way that did not involve him falling head first into his own house.

4 "Forget the Dog!"

October 30th, 1978

Eudora has Linus's beloved blanket, which she shockingly gives to the Cat Next Door. When Linus finds out, he insists that Snoopy fight the cat to get the blanket back, but Snoopy is too scared to do so immediately. Linus and Snoopy come up with a plan where Snoopy will act as a helicopter, flying Linus in to drop on top of the Cat, all to get the blanket back.

The storyline of Linus's blanket going missing was adapted into the French-Italian TV series known quite simply as Peanuts.

Things do not end up going great, as Linus, World War II, Snoopy, and somehow Woodstock all get themselves into a massive brawl. Charlie Brown announces the fight, but just moments later Snoopy gives up, leaving it as a bird, boy, and cat fight.