Shark

Sharks are recurring enemies in the Crash Bandicoot series.

Crash Bandicoot
Charles Zembillas, an artist for Crash Bandicoot, drew a concept picture for a shark enemy that was to appear in the game. Like a few other characters and enemies, this design was not used, but it was recycled for Crash Bandicoot 3: Warped.

Crash Bandicoot 3: Warped
The shark poses as an enemy in this game, there are blue sharks appearing in the Underwater levels (Under Pressure and Deep Trouble). It is seen wandering from left to right in a certain area, waiting for Crash. If Crash is hit by it, he will be eaten by the shark and it will spit out his scuba-gear the sharks can be defeated by spinning or torpedoes.

The shark also appears in (Tell No Tales and Hot Coco) there now white and red eyes. If Coco runs into a shark then it will eat her and spit out her jet ski the same as the other blue shark that eat Crash and spit out his scuba-gear from the Underwater levels.

Crash Bandicoot: The Wrath Of Cortex
Sharks return but are now red and a lot smaller than the ones in their previous game. These sharks appear in (Sea Shell Shenanigans, H2 Oh No!, Coral Canyon, and Crash and Burn). They can be defeated by a simple spin attack or, if in the submarine, by the torpedoes or mines. However, if Crash come into contact with one of them, he will be eaten up in one go except for his scuba kit.

Crash Bandicoot: The Huge Adventure
Once again, it returns to its blue color as an enemy the same from Warped in the underwater levels like (Shipwrecked, Shark Attack, Sunken City, and Air Supply) of The Huge Adventure. This time, if Crash gets hit by a shark without Aku Aku, he will turn into an angel instead eating him, like almost all of the deaths in this game. These sharks also act as the generic hazard of Dingodile's boss fight by constantly coming out from the left or right of the screen to cross.

Crash Bandicoot 2: N-Tranced
This time, one chases Crash while he's riding his surfboard with a meter at the left side of the screen to alert the player as to how close the shark is to them. When the shark is close enough, it will open its jaws towards Crash it appears in chase levels (Lagoony Tunes, Flockful of Seagulls, and Water Logged).

Crash Bandicoot Purple: Ripto's Rampage
A shark appears as a trading card in Crash Bandicoot Purple: Ripto's Rampage.

Crash Twinsanity
Sharks would have had another reappearance in Crash Twinsanity. As seen in concept art, it would have reprised its role as an enemy. However, like most previously-used concept enemies, it got scrapped during game development. It was set to appear in (Ocean Commotion. The shark did actually make a cameo in-game, at the beginning of the level High Sea Hi-Jinks), where if the player looks under the two frozen pools of water with nitro crates on them, they will see a huge frozen shark gaping towards the surface, with an updated model resembling the older one.

Crash Tag Team Racing
Sharks, in this game, act as the source of some of some Die-O-Ramas like Sharked, Soupy Swimmer and Jawed, and gags like Shark Bait. They utilize their Twinsanity model here.

Crash Landed
Sharks were going to appear in this game. They would be fused with bandicoots to make hybrids.

Trivia

 * In Crash Tag Team Racing, sharks are never seen in the Mystery Island area itself, only appearing in Die-O-Ramas and a gag video.
 * This is the only known enemy to appear in all Naughty Dog, Traveller's Tales, and Radical Entertainment games, and not be changed at all.