Klepto

Klepto is a condor first seen in Super Mario 64. Since then, he has continued to make infrequent appearances in the Mario series. His name is a pun on kleptomania, the inability to resist theft.

Buzzar from Paper Mario has a resemblance to Klepto.

Super Mario 64 / Super Mario 64 DS
In Super Mario 64, Klepto is seen in Shifting Sand Land. He holds a one of the castle's Power Stars, so Mario must reclaim it from his talons. Mario can attack the bird, knocking him out for short periods of time. Klepto will eventually regain his senses, and after losing the Power Star, he will attempt to steal who attempt to steal Mario's cap. Without his hat, Mario takes more damage when attacked. If he leaves and still has no hat, it will remain in the course he lost it in. Klepto has the same Power Star and purpose in Super Mario 64 DS. He also appears in another level, the Sunshine Isles, accessible from the Rec Room. He makes a final appearance in Tiny-Huge Island, when the character is big. He is carrying, as usual, a star - except this time it's a Power Star. Additionally, though Klepto only steals heroes' caps, he will attack and cause harm if he glances Yoshi in the vicinity even if Yoshi uses any cap.

Mario Golf series
In Mario Golf: Toadstool Tour multiple Kleptos (possibly other condors) can be seen flying on the Shifting Sands course.

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

Mario Pinball Land
In Mario Pinball Land  a group of four Klepto condors 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 Klepto-looking condors can be seen on the upper left side of the board.

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

Mario Party 5
In Mario Party 5, he has his own orb where, if landed on, Klepto will appear and take the character to another character's space determined by roulette, just like the Warp Space from Mario Party 4. In the instruction guide, Klepto's name is erroneously spelled Clepto.

Mario Party 6
In Mario Party 6, 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 will be 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, Klepto guards a treasure chest with a star. When the player arrives at Klepto's Ruins, his quest involves attempting to open the chest by entering the 4-digit code, giving them the hint that it is also his favorite word. When speaking, he has a tendency to stutter and repeat the word "for," indicating what the code is. By guessing the correct code (4444) and opening the chest, Klepto rewards the player with the Gaddget Map Maker. The ending states that Klepto changed the code to the treasure chest.

Mario Party 7
Klepto makes a small appearance 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.

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

Trivia

 * Klepto bears a resemblance to Neckies from Donkey Kong Country.
 * Klepto was erroneously spelled as "Kelpto" in Mario Golf: Toadstool Tour from the scoreboards.
 * Klepto also bares a very close resemblance to the Takkuri in The Legend of Zelda: Majora's Mask. In fact, the models are nearly identical, aside from some slight texture changes.