Peach's Crown

Crowns are items appearing many times in the Mario series on top of people's heads, mostly those of royalty.

Princess Peach
The crown of Princess Peach Toadstool is her emblem and a symbol of the Mushroom Kingdom. Toad Guards feature a picture of Peach's crown on their shields in Super Mario Galaxy. Princess Peach is typically seen wearing this crown. In Super Mario RPG: Legend of the Seven Stars, Princess Toadstool lost her crown during her wedding to Booster. Mario eventually found the crown on top of Booster's head.

Bowser
Bowser's crown is golden and is a symbol of his status of ruling over his kingdom. It does not appear in any games but it makes an appearance in every episode of The Adventures of Super Mario Bros. 3 on top of Bowser's head.

Princess Daisy
Princess Daisy also owns a crown as she is the ruler of Sarasaland. Her crown is orange, much like her dress, with several green-colored jewels, similar to her earings. In Super Mario Sluggers, her team's emblem is her crown surrounded by vines. The crown does not take any prominent roles other than appearing on her head in every game in which she appears.

Rosalina
Rosalina, much like Daisy and Peach, has a crown which is her symbol of royalty (she rules over the Galaxy). Her crown is tall and silver colored and it sits on top of her head. It does not have any notable appearances.

Other
Many other characters such as Queen Bean, Queen Bee and Big Bob-omb wear crowns as a symbol of their rule over a certain species and/or location. No crowns other than Peach's and Daisy's make appearances other than on top of their owners heads.