The orange ghost in the original Pac-Man is called Clyde.
Clyde is one of the four original ghosts in Namco’s 1980 arcade game Pac-Man. The classic quartet consists of Blinky, the red ghost; Pinky, the pink ghost; Inky, the cyan ghost; and Clyde, the orange ghost. Their distinct colors and behaviors helped make the enemies readable even on an early arcade screen.
Clyde is commonly described as the least consistently aggressive ghost. In the original game, he chases Pac-Man when he is far away but retreats toward his corner when he gets close. This gives him a different personality from Blinky, who directly pursues Pac-Man, and from Pinky and Inky, who try to intercept him.
The names can be confusing because the ghosts had different Japanese names and alternate English nicknames during localization. Clyde’s Japanese name was Otoboke, while the U.S. release also associated him with the nickname Pokey. Inky is cyan—not orange—and Blinky is the red ghost, making Clyde the only canonical answer here.