♦ Finn Mertens 💫 ♦

Finn has also proven to be a beginner at balloon music as shown in Marceline's Closet and has not yet mastered it.

Finn has repeatedly shown himself to be resistant to the Lich's mind control in "Love Mad," "The Lich," and "Escape from the Citadel," and Goliad in the episode of the same name; the real reason why is still unknown.

Finn is immune to electricity.
Finn is immune to electricity.

Finn has gained immunity to electricity thanks to a magical spring as seen in "The Charm of the Flute".

Finn is very skilled in various forms of combat, including hand-to-hand (punching, kicking, etc.), magic, and fighting with one of his many swords. He can jump incredibly high (this may be due to the lack of gravity on Earth because of the crater or because of the mutation he suffered during the Mushroom War, as other characters in the series don't jump as high as Finn) and is exceptionally strong and agile for a 16-year-old. Finn has some origami skills, as shown in "Ricardio the Lionheart" and "Marceline's Closet," where he makes a paper crane for Princess Bubblegum. Finn has been seen enjoying singing and, according to him, acquiring the ability to automatically adjust his commanding voice after eating a small computer. He is very good at playing a video game called Adventure Masters, which he and Jake play on BMO from time to time. Apparently, Finn can control his mind to feel no pain, as shown in "Jake's Suit."

Finn and his grass sword.
Finn and his grass sword.

Finn is somewhat gifted at building simple machines, such as the catapult in "The Witch's Garden." He can also spit over very long distances, as demonstrated in "Evicted!" when he spits on Marceline, and in "My Two Favorite People" when he spits in Tiffany's face. In "The Grotto," one of Jake's challenges was to beat a goblin in a spitting contest, which Finn would have easily won. Also, in "Who Could Win?", Finn spits on Jake during their fight. He has also been seen playing a flute in "Prisoners of Love," and he has a knack for beatboxing, a technique of creating sounds with the mouth. Another of Finn's notable abilities is his resourcefulness in emergencies; he's the one who has come up with most of the escape plans in episodes like "Frosted Out Wedding" and "Morituri Te Salutamus."

Finn wears a white hat that resembles a polar bear hat with two small ears, covering his entire head and only revealing his face (in Spain, it might have been mistaken for a rabbit hat). This hat is inspired by Bueno the Bear, a bear character created by Pendleton Ward (the series creator). In the episode "Little One," it's revealed that the hat is made of polar bear fur because at the end of the episode, Jake mentions that they're going to cut a bear's fur to make another hat. He also wears a light blue t-shirt, dark blue shorts, a backpack that's light green on top and dark green on the bottom, rolled-up white socks, and black shoes.

When he goes to sleep, Finn wears a red pajama set that covers him from his neck to his feet.

Finn in his underwear
Finn in his underwear

Her underwear consists solely of white briefs with a red elastic waistband, although sometimes they are completely white. In "Bonnibel Sweet Gum," she wears a bright blue swimsuit for swimming, which consists of a kind of blue shorts with a stripe across the top.

In "Together Again," after losing Jake, he can be seen wearing brown shorts and no longer wearing a shirt. However, previously in "Obsidian," he was wearing blue jeans.

Finn's hair is blond and curly. Previously, his hair was very long and straight, but he cut it to give to the Tree Witch, as she was going bald and wanted to look beautiful. This was in the episode "To Cut a Lady's Hair." Over time, Finn's hair grew back, but not as long as before. In some episodes, such as "Dangerous Love," "Heat Signature," "Apple Thief," and "Bellotopia," Finn is shown with shoulder-length hair. In the episode "Gotcha," Lumpy Space Princess sees that Finn has long hair (this was due to an optical illusion; it's unknown if it's entirely true).

Finn cuts his hair again in the episode "Davey," and he also dyes it dark brown. Later, it's shown growing back somewhat, but he's bald in the episode "Little Guy," where he appears from beginning to end. In the episode "The Great Human Bird," his hair is shown to have grown very quickly, and in "A Glitch Is a Glitch," his hair is as long as it was in his first appearance in the series. Throughout the episodes, his hair length varies, being short in episodes like "The Dungeon Train" and "Love Games." In "Escape from the Citadel," his hair reaches his shoulders. In "Obsidian," where he is officially seen as an adult, his hair is darker. He also has a beard. In "Together Again," when Finn is an old man, his beard is longer, and his hair is now gray.

Finn is a teenage boy, currently 17 years old, of average height and weight. His arms and legs are very thin, but he's a little chubby in the torso. He's missing several teeth because he often fights monsters that hit him in the face, and he also tends to bite rocks and other hard objects. These missing teeth are sometimes round or pointed and constantly change position, depending on the situation.

He often behaves in surprising and violent ways, but at times Finn is a brave and very fair boy. He has a strong sense of responsibility and gets upset when he can't help those in need. He is incapable of doing anything evil or unjust because it's not right. His behavior is that of a child, but when dealing with women, he acts chivalrously. He is very sensitive and tender; when he's in love, he doesn't know how to act around girls and doesn't readily express his feelings.

Finn aspires to be a great hero who safeguards the Land of Ooo and protects any innocent creature or person, a trait he inherited from his greatest idol, Billy. He's somewhat naive, and this sometimes leads to a lot of conflicting emotions when he's unsure whether something is good or bad. Finn has a number of fears and phobias that test his courage and heroism.

One of Finn's biggest fears was the ocean.
One of Finn's biggest fears was the ocean.

For Billy!
For Billy!

One of Finn's most notable phobias is the ocean. Finn goes crazy with the slightest contact with seawater. He is, in terms of his phobia, a thalassophobe, since Finn can swim in rivers or any other body of water, but not in oceans, and it is the ocean in particular that terrifies Finn.