Humans

Humans are a critically endangered species in the Land of Ooo. It is hinted that they were driven to near extinction roughly a thousand years before the events of Adventure Time during an event called the Mushroom War.

Current Status
Many residents of the Ooo are under the impression that humans no longer exist as demonstrated by Bob and Ethel Rainicorn in "Her Parents." Due to their rarity, many characters marvel at Finn's humanity, such as Princess Bubblegum in the episode "Susan Strong."

There are several other beings that resemble humans in the Land of Ooo, such as Penny, Phil or the Old Man Henchman. Despite their resemblances, most of these beings are not recognized by other characters to be humans. According to the show's writers, these characters should be referred to as humanoids or mutants. Some of these beings, however, were actually humans in the past, which includes Ice King, Business Men, and Moe.

Finn was the only confirmed human until "Betty" when Simon accidentally brings Betty into the future, and in "Billy's Bucket List " when Finn's father, Martin is revealed to be alive, both look strikingly different from the alternate timeline's presumably unmutated humans, who have regular-sized eyes with visible whites and pupils, as well as more prominent noses. However, the humans in Pendleton Ward's other series, Bravest Warriors, also have little black eyes and no noses.

Known humans

 * Finn
 * Princess Bubblegum
 * Martin
 * Betty Grof
 * Fionna (fictional)
 * Prince Gumball (fictional)
 * Flynn (Comic only)

Deceased humans

 * Abraham Lincoln
 * Commander and Private (Animated Movie)
 * Marceline's mom (confirmed at Wondercon 2013)

Known former humans

 * Simon Petrikov (now a wizard)
 * Moe (now a cyborg)
 * Randall N. Byron (now computer software; Comic only)
 * Business Men (now mutants)

Hybrid humans

 * Marceline (Human/Demon)
 * Jay & Bonnie (Human/Pillow hybrid)
 * Stormo (by DNA)
 * Adventure Tim (Human/Dog hybrid; Comic only)

Humans from the Farmworld timeline

 * Finn Mertens
 * Finn's mom
 * Finn's Dad
 * Finn's Baby Brother
 * Choose Bruce
 * Destiny Gang
 * Big Destiny
 * Trami
 * Tromo
 * Unnamed Destiny Gang Members