Klepto

A Klepto, also known as Klepto the Condor or Big Bird, is a larcenous, heavy-lidded condor that first appears in Super Mario 64. Since then, they have continued to make infrequent appearances in the Mario franchise. Their name comes from "klepto-", a prefix originating from Ancient Greek and meaning "theft."

Super Mario 64 / Super Mario 64 DS
In Super Mario 64, a Klepto is seen in Shifting Sand Land. It holds one of the castle's Power Stars, flying around between the course's four pillars so Mario must reclaim it from its talons. Mario can attack the bird, knocking it out for a short period of time. The Klepto eventually regains its senses, and after losing the Power Star, it attempts to steal Mario's cap. In later stages, it can be found near the oasis and still attempts to steal his cap. If it does manage to steal it, it will fly around the pillars carrying it similar to before. If Mario leaves and still has no cap, it remains in the course he lost it in.

The Klepto has the same Power Star and purpose in Super Mario 64 DS. Another Klepto also appears in another level, the Sunshine Isles. A third one makes an appearance in Tiny-Huge Island when the character is big. Additionally, while Kleptos steal Mario's, Luigi's, and Wario's caps, they can damage Yoshi.

Super Mario Odyssey
In Super Mario Odyssey, a Klepto is encountered upon reaching the Lost Kingdom. It takes Cappy from Mario and retreats with him on a pedestal, made up of two platforms: one that is raised, and one that is lower. To get Cappy back, Mario must lure Klepto into sitting upon the lower platform, and then Ground Pound the higher one, making the platform Klepto is sitting upon shoot up and defeat it. A Klepto appears again in a Moon Pipe sub-area in the same kingdom, and is defeated in the same manner.

Unlike the Kleptos of Super Mario 64, this Klepto has two toes pointing forward and one pointing backward on each foot. It shares this trait with the Kleptos of Mario Pinball Land. Also, its design is somewhat different from previous games, with two tufts of hair, visible purple bags underneath its eyes, and a constant frown instead of a tired-looking expression.

Mario Golf series
In Mario Golf: Toadstool Tour multiple Kleptos can be seen flying on the Shifting Sands course. Klepto's name (erroneously spelled as Kelpto) can be seen sometimes on the scoreboard of a golf match.

A Klepto also appears in Mario Golf: Advance Tour in the back of the Marion training grounds, in which the player must rescue a Koopa Troopa hanging from its claws.

Mario Pinball Land
In Mario Pinball Land  a group of four Kleptos can be seen flying around the pyramid in the Shifting Sands world. If Mario defeats them, he gets a star.

Mario Party 3
In the background of Spiny Desert, three Kleptos can be seen on the upper left side of the board, playing tic-tac-toe.

Mario Party 4
A Klepto also appears in Mario Party 4 on Shy Guy's Jungle Jam. Players can pay it five coins to be transported to the other side of the board, collecting coins in the process. In Paths of Peril, Klepto picks up players that fall off the stage.

Mario Party 5
In Mario Party 5, a Klepto has its own orb where, if landed on, it appears and takes the character to another character's space determined by a roulette. They also cameo in the minigame Fish Upon a Star. In the instruction guide, Klepto's name is erroneously spelled Clepto.

Mario Party 6
In Mario Party 6, a Klepto can be seen flying in the background of Pokey Punch-out. The Klepto Orb returns as an orb that can only be placed on a space. Any player who lands on it is taken back to the start of the board. In the Solo Mode board Thirsty Gulch, another Klepto can be seen flying around the board.

Mario Party Advance
In Mario Party Advance, a unique Klepto guards a treasure chest at Klepto Ruins.

Mario Party 7
A Klepto makes a few small appearances in Mario Party 7. Landing on one of the Green Spaces in Bowser's Enchanted Inferno! causes Klepto to grab the Star and move it to another location. Klepto can also be seen in cube form as the tops of totem poles on the Neon Heights board.

Mario Party 8
A Klepto makes a minor cameo appearance in Mario Party 8, holding up the sign at the 5000 point mark for the minigame Test for the Best.

Mario Tennis Aces
In Mario Tennis Aces, Kleptos can be seen in the background of Bask Ruins. Unlike in Super Mario Odyssey, these Kleptos' design are now an updated version of their design from Super Mario 64 to Mario Party 8.