Princess Peach (casually Peach, known as Princess Toadstool and occasionally referred to as simply Princess) is the princess of the Mushroom Kingdom, and the love interest of Mario. She resides in her castle along with many Toads, who act as her loyal servants. Her kingdom is often attacked by Bowser and his minions.

Peach has an affinity for the color pink, which accents her gentle personality and kind temperament. Peach's kind nature and role as the damsel in distress are often represented with her heart abilities and crown emblem.

Peach is shown to be a sweet, kind, polite, and optimistic person, while also being classy and sociable, with more and more portrayals further displaying her as clever and adventurous. She apologizes excessively for getting into trouble and requiring Mario to rescue her. She even shows concern and compassion towards her enemies frequently, such as saving Mimi even after she mocked and fought her or making a thank-you cake for Bowser for his part in saving the day, even though he intended to kidnap her right after. She can sometimes be assertive when it comes to standing up for her friends.

Largely because of her frequency of being kidnapped, she has been the subject of a running gag in throughout the series where several characters refer to the frequency of her abductions. Even Peach herself has referred to her kidnapping as a "recent kidnapping". Some characters referred to her even being useless. But while Peach is often considered the archetypal damsel in distress, she is often shown actively working against her captors, sneaking around searching for power-ups and/or information to send to Mario, and even attempting to escape her confinement.

While Peach occasionally seems naïve, she is generally level-headed, knows when to take charge, and shows more common sense and observance than those around her, such as being the only one to notice a Mario doppelganger in the Isle Delfino vacation, insisting that an emergency meeting continues even after it is briefly interrupted by Bowser and deducing what Fawful was planning regarding her, and talking a stubborn Bowser into joining her and Mario. She often acts as a peacemaker; she is a motherly figure to the young Yoshi and the Toads, she is practical and generous to a fault, such as trying to convince the Mario Bros. to return home, despite the fact that King Koopa is still after her. She also has a feisty side, which shines through particularly well in her. Besides sports, Peach is also into ballroom dancing, video games, and gardening, and seems to enjoy exploring and trying new things.

Although she is generally depicted as kind, sociable, and generous most of the time, her having a diva-like side, with her being eager to get photographed and striking poses, though, she regains her composure and generally acts as she usually does. A similar temperamental nature can be trigger through constant failure, sometimes either stomp her foot in frustration or otherwise put her hand over her head and scream repeatedly in frustration before proceeding to wince, in either case can cause Yoshi's to crouch down in fear.

Peach can also show the braver side of her personality; participating as a fellow heroine, or in the latter two cases, as the sole heroine, single-handedly saving the day.

She largely spoke with a mature, feminine tone, Peach spoke with a slightly higher-pitched, somewhat shrill tone, and also possessing a slight Italian accent. She currently has a very soft, high-pitched voice.