One of the most well known attributes of turtles and tortoises is that they're not exceptionally fast and nimble animals. Between their heavy shells and short legs, they're not very well suited for quick, speedy movement, and as such have evolved to be more reliant on their thick armor for protection than in outrunning danger.
This is often carried over in fiction, sometimes to the point of exaggeration. Fictional turtles tend to be ridiculously slow, sometimes to the point of seeming to move — or even speak — in slow motion.
There are two general ways this trope is often employed. Sometimes, the turtles' slowness is equated with patience and endurance in contrast with hurry and impatience, a la The Tortoise and the Hare, with the turtle's plodding but steady progress reliably getting it where it needs to go, even if not in a very flashy way. Other times, it is combined with the turtle's natural and seemingly impenetrable armor to create a Stone Wall or Mighty Glacier-type character, slow and not necessarily very strong, but capable of weathering almost any attack. Together, these two attributes create characters that rely on their trusty defenses to patiently endure the attacks of more hotheaded, brash foes and wait until they give up in boredom or frustration — something based off of the way turtles defend themselves in real life, retreating into their shells and waiting for would-be predators to give up and leave before coming back out.
In real life, turtles may not be the most agile animals around, but they're nowhere near as slow as fiction makes them out to be. Sea turtles can be quite speedy when they need to be, especially in the water. The part about them being well-defended is absolutely Truth in Television, especially for land-dwelling tortoises (but, again, sea turtles are something of an exception — an overly thick shell would harm their buoyancy, and the leatherback sea turtle does not have a bony shell at all: its back is covered by thick skin alone).
- Comcast Cable has, as their mascots for high speed Internet, the speed-hating Slowskys — a husband and wife turtle couple.
- Sgt. Frog: One episode has Tamama coming across a tortoise in the countryside, plodding along the same path day after day. It's revealed later on that Fuyuki had that tortoise as a pet but lost it several years ago, and it's done nothing but make its way back to its breeder ever since. It eventually succeeds.
- Shirokuma Cafe: Tortoise moves and talks very slowly.
- Magic: The Gathering: Meandering Towershell, a very large turtle creature, is notable for having its slowness written in as a mechanic. Instead of attacking normally on the turn when it's activated, like most creatures do, it's removed from battle for a turn, and in the next turn it returns into play and deals damage to its target, representing the slow process of the Towershell plodding over to its foe and attacking.
- Archie Comics' Sonic the Hedgehog: Tommy Turtle's character in a nutshell, or rather in a turtleshell; slow, patient, and pretty durable. His debut issue even revealed that he and Sonic had a very Tortoise and the Hare-esque race as kids (Sonic had taken on a disguise as a Hare named Juice and as such the story was recounted as a turtle racing a hare).
- The Flash: While not an actual turtle, one of the Flash's foes is a turtle-based villain, complete with super-slowness and a launchable shell.
- One of the most famous of Aesop's Fables, The Tortoise and the Hare, tells of a race between a proud, speedy hare and a slow, plodding tortoise. The hare, being the fastest animal around, has no doubts that he will win, quickly gains a large lead and stops partway through to nap under a tree, confident in his advantage. The tortoise instead keeps making his slow but steady progress towards the finish line. By the time the hare finally wakes up and realizes that the tortoise has passed him and is approaching the finish, it's too late for even his speed to close the distance and the tortoise wins. The moral of the story is not to let oneself be blinded by arrogance, and that determination and perseverance can make up for a lack of natural advantages.
- Dungeons & Dragons: The third-party DragonMech setting has humanoid turtles called tortogs, notable for their ability to Feel No Pain from anything that doesn't punch through their very thick shells — and it takes quite a lot to break their shells. This has resulted in them becoming an entire species of smugglers and traders in the setting's present, as they're the only ones capable of withstanding the agonizing rains of micrometeorites that pelt the world on a nightly basis and forced almost all other species to retreat underground or inside city-sized Giant Mecha.
- In Candy box! and its sequel, using the turtle potion will turn you into a turtle that moves at a slow speed but has much higher defense. This is vital for surviving some bosses, especially those that deal incredible amounts of damage.
- Iron Marines: The Tortugons — turtle-shaped walking tanks — have a giant amount of health. The bad news is that they're all slower than molasses.
- Mega Man:
- Rainy Turtloid of Mega Man X6 is a tortoise-based robot who is built with high defenses to withstand high levels of pollutions and made to work for a pollution survey team. As a boss, his shell makes him nigh invincible, except for attacks at his weak points.
- Mega Man Zero 4: One of the bosses, Heat Genblem, is a robotic tortoise. He's fond of a particular tactic during combat where he walks slowly forward, then, when an attack comes, he immediately turns his back to guard himself. If he's attacked further in that state, he'll do a Counter Attack with an Elemental Punch. In general, both his shell and his battle pattern makes it hard to find an opening to hit him.
- Minecraft: Sea turtles, while having no form of attack and not being particularly fast (at least on land), have substantially higher health than most other mobs and over twice the usual amount of health for passive mobs. Their shells can also be used for brewing the Potion of the Turtle Master, which when drunk gives players a large defense bonus while drastically cutting their maximum movement speed. Of note is that enhancing the effect of said potion via Glowstone will make a player slow to a crawl via a -90% speed reduction... but also gives them 120% Damage Reduction which makes them invincible against most forms of damage.
- Pokémon has featured a number of turtle-based Mons over the years, most of them fitting this trope to one degree or another. They tend to have good defense (the stat the determines by how much or how little incoming attacks are reduced) and health (the total number of health points a Pokémon has), but their speed (the stat that determines which priority a Pokémon's actions get in the games' turn-based battle system) tends to be middling at best and very low at worst.
- Torkoal, a Fire-type introduced in the third generation games, is an archetypal Stone Wall — it has an abysmally low speed stat, but very good physical defense.
- Turtwig and its evolutions Grotle and Torterra, Grass- and Ground-types based off of the idea of the Turtle Island, tend more towards being Mighty Glaciers — they have very good defense and health coupled with respectable attack, but their speed remains very low. In point of fact, Torterra is one of the slowest Pokémon among all the fully evolved starters.
- The sea turtles Tirtouga and Carracosta have excellent defense, and are also Rock-types, an elemental type that tends to have a lot of resistances in the games' Elemental RockPaperScissors. Combined with one of their abilities, Solid Rock, which reduces the damage done by moves that would normally be super-effective against them, they are very well suited to tanking out damage. They need this, because they are also very, very slow.
- Generation Seven's Turtonator, much like its predecessors, is both very slow and provided with excellent defenses. It can avert this trope if it learns the move Shell Smash, which is themed around the idea of a Pokémon smashing off part of its shell in order to become a fair bit speedier — but at the cost of losing some of its defense.
- Saurian: Most of turtles avert this — a fair number of them, being softshell turtles, are surprisingly fast, and most are capable of defending themselves. Basilemys, however, plays this straight, as it primarily defends itself by retreating into a shell that only Tyrannosaurus rex can hope to break.
- The Lion Guard: Besides moving slowly, Kongwe the Wise Old Turtle prefers to take things at a slow and calm pace, making observations along the way. Fuli is initially exasperated by this due to the fact they're in an Escort Mission (and, being a cheetah, she would rather do everything fast), but she gradually takes her advice to heart, especially when it becomes useful in defeating Makucha.
- My Little Pony: Friendship Is Magic: In "May the Best Pet Win!", Rainbow Dash holds a contest to choose a new pet, and one contestant is a tortoise. Rainbow is highly unimpressed, particularly since she wants a fast pet to keep with her racing and the tortoise is anything but, something most clearly evident in a race Rainbow holds to judge the speed of the prospective pets and all the other animals complete three full circuits in the time it takes the tortoise to take a single step.
- The tortoise still wins the competition: in the last trial, a breakneck race through a dangerous gorge, all the other animals shoot ahead — but they also leave Rainbow in the dust when she's trapped by a landslide. The tortoise, however, walks up to her and slowly begins to dig at the rubble, pushing it away bit by bit until Rainbow is freed, and then just as slowly carries her to the finish line. Rainbow chooses him as her pet due to his loyalty and tenacity, naming him Tank to reflect his "never give up, can-do attitude". Also, the exact win condition of the race was to cross the finish line with her.
- In the last scene, Tank completes one of the earlier trials — stealing the ill-tempered cat Opal's favorite mouse toy — by goading Opal into attacking him, letting her waste her furious claw swipes on his shell while he calmly reaches over to grab the toy.