Shaman

Shamans are a people first appearing in the game Super Mario RPG: Legend of the Seven Stars, where they act as both NPC shopkeepers and enemies. The later made a re-appearance as non-enemy NPCs vital to the plot of all three of the Paper Mario series games.

The Shamans in Super Mario RPG: Legend of the Seven Stars are all identical, while those later introduced in the Paper Mario series have individual characteristics, as well hair, which they did not before.

Super Mario RPG: Legend of the Seven Stars
Shamans are first encountered near The Sea area and the Sunken Ship as shopkeepers, selling Mario and his party items and weapons.

They later appear in the Belome Temple, again, as merchants. Mario later battles them as enemies in both Nimbus Land and Bowser's Keep. These magical beings are very weak to physical attacks, while having a strong magical defense.

Paper Mario
Merlon and his family, appearing in Paper Mario, Paper Mario: The Thousand-Year Door and Super Paper Mario, greatly resemble Shamans. Interestingly, Merlon and his family appear in each Paper Mario game, but have different appearances and differences in personality.
 * Merlon
 * Merlee
 * Merluvlee
 * Merlow

Paper Mario: The Thousand-Year Door
Wonky reveals in Paper Mario: The Thousand-Year Door that they may be a part of a sort of clan that names their members after their purposes, explaining their sporadic appearances in different lands.

Trivia

 * In Paper Mario: The Thousand Year Door all the Paper Mario Shamans but Merlow and Merle returned.