Pizza

A pizza is an Italian type of food, consisting out of a large pie made out of dough, covered with tomato sauce and mostly cheese, but sometimes other things can be put on it like pineapple, pepperoni, mushrooms etc. Pizzas are one of the most favorite food in the world. Currently there are plenty different types of pizzas.

Mirage Comics
Pizza occasionally appeared in the Mirage universe.

In "Totally Hacked!", Using a million dollars he had in his pocket, Gnatrat buys a restaurant (employing Splinter as a waiter) and lures Supperman in with an All You Can Eat promotion. They prepare the final dish, which is unfortunately pizza, and it attracts the Ninja Turtles to the restaurant. Splinter begins to tell his sons to back off from the pie, but Gnatrat gets too absorbed in his “boss” role and starts ordering Splinter around. Incensed, Splinter feeds the pizza to the Turtles just to tick Gnatrat off.

In "The Treaty", Leo is racing across the rooftops of New York, hoping to get back to April O'Neil’s apartment with a fresh pizza. Unfortunately, he undergoes another one of the after effects from his recent time/space adventures and finds himself zapped to the world of Usagi Yojimbo yet again. While there Leo drops his pizza. Tomoe Ame picks up his trampled pizza box, disgusted by the quality of the contents within. Taking the pizza, Leo attempts to explain that normally it’s very appetizing, but before he can finish, the time/space effects wear off and he vanishes. Back in April’s apartment, the Turtles are a bit ticked that Leo’s taking so long with the pizza. Suddenly, he comes smashing through the window and lands face-first on the floor. Not only has he missed the entire movie and ruined the pizza, but now he’s broken April’s window.

In Teenage Mutant Ninja Turtles Attack!!! Part 1 the Turtles are arguing over where to stop for dinner. Michelangelo suggests pizza, but Leonardo vetoes the idea, as pizza makes him gag.

In The Name is Lucindra, Raphael owes Lucindra a pizza after losing to her.

In Raphael: Snapper, Raph sits on the couch in front of the tube, nursing indigestion after eating six pepperoni pizzas. Looking to his left, he spots a glass bowl containing a tiny snapping turtle. Amused, Raph plucks the turtle up by its tail, only to have it bite his finger. The pain and the indigestion prove too much for him, and Raph passes out. Suddenly, Raph finds himself in a nightmarish version of April’s apartment, approached by a humongous mutant snapping turtle. Tearing Raph’s throat out with his jaws, the snapping turtle says that pizza is no substitute for blood.

In The Haunted Pizza, a cheese factory drilled deep into the ground to create gigantic warehouses for their product. Eventually small portions of Ooo-Zah were able to make their way through hairline cracks into the factory, and begin growing on the cheese. Eventually the cheese was processed and shipped to pizza factories... and of course, April brings the pizza containing Ooo-Zah home.

In Memories of the Future, Casey passes out in front of the tube, having eaten too much pizza.

Teenage Mutant Ninja Turtles (1987 series)/Archie Comics
The 1987 cartoons are, along with the comics based on them, a TMNT universe in which the Turtles all share an intense affinity for pizza, particularly Michaelangelo. They are hardly ever seen eating anything else; however they are very flexible with what toppings they like on their pizza, experimenting with all sorts of items in every possible combination including clams, tuna, sauerkraut, chocolate, ice cream, bananas, jelly beans and peanut butter.

The Turtles always get their pizzas by going on the streets to a pizza parlour, dressed so no one could see that they are mutant turtles. Sometimes all four go, sometimes only one goes.

Pizzas are also the Turtles weakness. The Shredder is aware of this, as many of his plans to destroy them involve pizza (like the episodes The Case of the Killer Pizzas, Pizza by the Shred etc.).

In some other TMNT universes, the Turtles eat other things, mostly sushi.

Films
The turtles also eat pizza in the film series. Except in the third film, they are not seen eating pizza but despite it not appearing, pizza does get mentioned.

2003 Series
Pizza occasionally appeared in the 2003 TV series.

Apparently the Turtles liked pizza as kids (Attack of the Mousers).

The Turtles ate pizza off-screen in Darkness on the Edge of Town.

Casey Jones eats pizza in The Way of Invisibility.

There was an episode where Leonardo was sleeping with a slice of pizza in his hand

In The Shredder Strikes Back, Part 1, you can see open pizza boxes when the turtles are sleeping.

The Turtles are seen eating pizza as kids in the episode The Lesson.

Michelangelo talked about wanting pizza in Enter the Dragons, Part 2.

Turtles Forever (2009)
At the end of Turtles Forever, the Mirage Turtles, after having encountered the 1988 Turtles and their 2003 counterparts, suggest to go eat some pizzas. Since the Mirage Turtles rarely ate pizza in the Original Mirage Comics, they are obviously influenced by their '88 counterparts.

Teenage Mutant Ninja Turtles (2012 series)
In their fifteen years growing up in the sewers, the Turtles primarily ate algae and worms prepared in various dishes. When they were finally allowed to go up to the surface, Raphael playfully scares a pizza delivery guy and causes him to drop a pizza box. Not knowing what it was at first, the Turtles investigate it and Michelangelo volunteers to taste it. It was so good (his brain exploded from the flavor) Mikey at first tried to convince his brothers it was terrible so he could have it all to himself, but they weren't convinced - after eating the pizza they determined it was a huge improvement over worms and algae. Pizza had since become the Turtles' favorite food, particularly Mikey's, but there are times in which the turtles eat other food (such as ramen).

In subsequent episodes Michelangelo is seen making various dishes out of pizza. Mikey has also been revived with a slice of pizza after a fight with Snakeweed left him unconscious.

Video Games
Pizza is often used as a health power-up in the video games.

Trivia

 * Remember all of those wacky pizza toppings the Turtles would put on their pizza in the 1987 cartoon? James Rolfe (better known as the Angry Video Game Nerd) got a few friends together and actually shot a video of the group trying the pizzas as seen in the show. The reactions were pretty much what you'd expect from such classics as an anchovy and hot fudge pizza would yield, though some of them weren't bad. The general consensus, though, was that Donatello actually has good taste in pizzas, while Michelangelo's were utterly horrible. He also made a video as "Board James" about the TMNT board games.