Mario's Glove
Mario's Gloves are a part of Mario's clothing. He wears them in every game, except the first games, (i.e. Donkey Kong or Donkey Kong Jr.) and in games where he is a baby. Other characters that have gloves include Luigi, Wario, and Waluigi.
Mario's Gloves don't have that much significance in most games, but in Luigi's Mansion Mario loses one of his gloves and Luigi has to find it. After inspecting Mario's Glove, Madame Clairvoya claims that it is extremely sweaty.
Intriguingly, Master Hand of the Super Smash Bros. series bears a striking resemblance to one of Mario's Gloves, particularly in Super Smash Bros., and to a lesser extent in later titles.
In the Mario & Luigi series, the player can change Mario or Luigi's gloves so they can have a special power, raise stats, or heal the player's HP (see Clothing for more details).