An Adept (エナジスト Energist) is a person in the Golden Sun series who can use Psynergy. They were called Jenei (ジエネス Jienese) in the ancient past. There are five types of Adepts, one for each of the elements—Venus (earth), Mars (fire), Jupiter (wind), and Mercury (water)—and a fifth non-element class called "Dark Adepts" or the "Umbra Clan" (Umbra being Latin for shadow).
As mentioned, Adepts are people with the ability to use Psynergy. Adepts are usually aligned with a specific element, and thus Adepts are often classified by that element, for example, an Adept that manipulates earth or plants is referred to as a Venus Adept. Generally, Adepts can only cast Psynergy of their own elements, but spirits known as Djinn (singular: Djinni) can grant Psynergy of other elements if the Djinni's element is different from the Adept's.
In modern time, Adepts are scattered throughout Weyard and tend to be located near sources of great Psynergy. Often this source is a deposit of Psynergy Stones, like those within Mt. Aleph and the Elemental Rocks. Elemental Lighthouses are also possible sources, giving birth to the Mercury Clan and explaining why everyone in Prox is a Mars Adept (Prox lying just south of the Mars Lighthouse) despite the frigid climate. The most notable exception is Lemuria, where all the city's denizens are Mercury Adepts, yet without an obvious source for this Psynergy. Alternatively, a regular person's Adeptness to Psynergy can be unlocked via direct contact with a Psynergy Stone. This method is the known source of power for Feizhi, who became a Jupiter Adept, and Eoleo, who developed the powers of a Mars Adept.
One sign of an Adept involves the person's sensitivity to Psynergy use. Adepts are usually able to sense when Psynergy such as Mind Read is being used on them. Adepts can also apparently see the actual usage of Psynergy, rather than just the outcome.
In ancient times, Adepts were known as Jenei. The Jenei were said to rule the world, and with their powers, they created various machinery that harnessed the power of the elements. It is implied that the Jenei were divided into various tribes, each of which ruled various portions of the world. One tribe of Jenei, known as the Neox, was noted to specifically watch over what is now known as the Ei-Jei region, and was allied with the Exathi, a race of skilled craftsmen. Over time, the Jenei became dissatisfied with simply ruling, and made an attempt at omnipotence by attempting to control the fundamentals of Light and Darkness. The resulting cataclysm led the Jenei to lock up the machines responsible, in the hopes that they would never be used again. At a later time, constant warfare led a group of people to seal away Alchemy, which resulted in the disappearance of most members of the race. Left behind were small groups of Adepts located near powerful sources of Psynergy. In addition, the Jenei left behind certain aspects of the culture for usage by future generations.
By the time of Golden Sun, Adepts as a race were unknown, partly due to isolation, and partly due to the fact that many Adepts specifically made a point of hiding their powers. One such group of Adepts was located in the village of Vale, near the foot of Mt. Aleph. The existence of Adepts would slowly become known to small groups of people due to the efforts of the Warriors of Vale, a group of young Adepts who journeyed the world in an attempt to revive Alchemy, which was needed to revive the world. During their journey, the Warriors of Vale met up with other groups of Adepts around the world, many of whom were unaware of the true origins of their abilities. They also found out that as a result of the eruption of Mt. Aleph, random humans became Adepts via encounter with Psynergy Stones. In some cases, the Adepts would reveal their powers to groups of people.
Following the Golden Sun event, Adepts became known throughout the world, with several countries attempting to hire Adepts as mercenaries to assist in their countries' expansion efforts. Thirty years after the Golden Sun event, the some of the history of the Jenei was discovered by Matthew's group of Adepts, during their travels across Angara. Matthew's group discovered a Glyph Book that allowed for translation of the Jenei's language, and also reactivated some of the ancient Alchemy Machines. During these travels another type of Adept came to light, Dark Adepts, who could wield Dark Psynergy. Furthermore, it is implied that a sixth type, Adepts who could control Light, also appeared as a result of exposure to the intense light of the Apollo Lens.
 List of Adepts
Isaac - A Venus Adept and the main protagonist of Golden Sun (he remains playable in The Lost Age). Isaac was born in Vale and is good friends with Garet and Jenna. He can be considered the main character of the Golden Sun series in general. As an adult, he resides in a cabin on Goma Plateau, where he observes Mt. Aleph. He has also appeared as an Assist Trophy in Super Smash Bros. Brawl.
Garet - A Mars Adept and a playable character in both Golden Sun games. Garet was born in Vale and is Isaac's childhood friend. As an adult, he resides with Isaac in a cabin on Goma Plateau, where the two observe Mt. Aleph.
Ivan - A Jupiter Adept and a playable character in both Golden Sun games. Ivan, although born in Contigo, was raised by Hammet in Kalay. Hammet entrusted Ivan with the Shaman's Rod, an ancient treasure that, unknown to Ivan, plays a vital role in their quest. By the time of Dark Dawn, Ivan resided in Kalay, and invented the Soarwing
Mia - A Mercury Adept and a playable character in both GBA Golden Sun games. Mia was born in Imil and is among the last members of the Mercury Clan.
Felix - A Venus Adept and the main protagonist of Golden Sun: The Lost Age. Felix was born in Vale and is Jenna's older brother.
Jenna - A Mars Adept and a playable character in The Lost Age (Jenna is also playable in Golden Sun, albeit fairly briefly). Jenna was born in Vale and is Felix's younger sister. She eventually marries Isaac prior to Dark Dawn, and has a son named Matthew.
Sheba - A Jupiter Adept and a playable character in The Lost Age. Sheba was raised in Lalivero, although it is strongly hinted that she comes from Anemos.
Piers - A Mercury Adept and a playable character in The Lost Age. He was born in Lemuria. Piers is the only playable character in Golden Sun: The Lost Age who was not introduced in Golden Sun.
Matthew - A Venus Adept and the main protagonist of Dark Dawn. He is the son of Isaac and Jenna, and lives with Isaac at the Lookout Cabin at Goma Plateau.
Karis - A Jupiter Adept and a playable character in Dark Dawn. She is the daughter of Ivan, and good friends with Matthew and Tyrell.
Tyrell - A Mars Adept and a playable character in Dark Dawn. He is the son of Garet and Matthew's best friend. He resides at the Lookout Cabin with his father, Isaac, and Matthew.
Rief - A Mercury Adept and a playable character in Dark Dawn. He is the son of Mia and the younger brother of Nowell. He travels the world with Kraden as one of Kraden's apprentices.
Amiti - A Mercury Adept and playable character in Dark Dawn. He is a prince of the water kingdom Ayuthay, and the chosen bearer of the Insight Glass.
Sveta - A Jupiter Adept and a playable character in Dark Dawn. Sveta is a Beastman, a demi-human race that mutated in response to the Golden Sun.
Eoleo - Briggs and Chaucha's son. Initially introduced in The Lost Age, Eoleo was not born with the ability to use Psynergy, but instead is among those whose latent abilities were awakened by falling Psynergy stones. He is revealed to be a Mars Adept in Golden Sun: Dark Dawn, where he becomes a playable character.
Himi - A Venus Adept and playable character in Dark Dawn. She is a seer who possesses powerful Psynergy and can see the future. She is a priestess of Yamata, daughter of Susa and Kushinada, and sister to Takeru.
Saturos - A Mars Adept and a boss in Golden Sun. Saturos was born in Prox and is Menardi's partner. He and Menardi unintentionally cause the storm at the beginning of Golden Sun and are the only Proxians to survive.
Menardi - A Mars Adept and a boss in Golden Sun. Menardi was born in Prox and is Saturos's partner. She is Karst's sister. She and Saturos unintentionally cause the storm at the beginning of Golden Sun and are the only Proxians to survive.
Alex - A Mercury Adept and an antagonist in all three Golden Sun games, although he is never battled. Alex was born in Imil and is among the last members of the Mercury Clan. Unlike Mia, Alex abandoned his duty and seeks to light the Elemental Lighthouses. Alex could be considered the main antagonist of the Golden Sun series in general.
Agatio - A Mars Adept and a boss in The Lost Age. Agatio was born in Prox and is Karst's partner.
Karst - A Mars Adept and a boss in The Lost Age. Karst was born in Prox and is Agatio's partner. She seeks revenge on Isaac for defeating her sister, Menardi.
Blados - A Dark Adept and boss in Dark Dawn. Partner to Chalis and member of the military nation of Tuaparang. Master Swordsman. Manipulates the party for most of the game for mostly unknown reasons.
Chalis - A Dark Adept and boss in Dark Dawn. Partner to Blados and member of the military nation of Tuaparang. Uses her beauty and charm to manipulate people. Manipulates the party for the most of the game for mostly unknown reasons.
 Minor characters
 In Golden Sun
Aaron - Garet's younger brother. Aaron returns briefly in the ending sequence of The Lost Age. His element is never revealed, but his red hair and relation to Garet may be a sign that he is a Mars Adept.
Dora - Isaac's mother and Kyle's wife. Dora returns briefly in the ending sequence of The Lost Age. Her element is never revealed, but she's most likely a Venus Adept.
Tret - One of the guardian spirits and "father" of Kolima Forest. After Mt. Aleph erupted, some Psynergy stones hit his branches, granting him a strange type of power in the process. Because the Kolima lumberjacks, hired by Lady McCoy from Bilibin, lifted their axes against him and the forest, he filled with rage and cursed the people of Kolima to turn into trees and die with the forest. Once Isaac and his friends defeat his angered self and revive his kind self, he uses his Psynergy to free the people from the curse. His element is never mentioned, but he's assumed to be a Venus Adept, since he has the power to turn people into trees and the attacks he uses in battle are Earth element attacks.
Laurel - One of the guardian spirits and "mother" of Kolima forest. Along with Tret, she was struck by Psynergy stones and was granted Psynergy, but unlike Tret, Laurel was filled with sorrow, this being the reason why her powers are different from Tret's. Once the party saves Tret and the forest is revived, Laurel foresees an evil forest in the way of Isaac's path and gives him advice to proceed with caution.
Feizhi - The daughter of Master Feh whom once studied under Hama. Feizhi may return briefly in a data-transferred game of The Lost Age. She was not born able to use Psynergy, but instead is among those whose latent abilities were awakened by the falling Psynergy Stones. Feizhi is assumed to be a Jupiter Adept because of her ability to predict the future.
Hama - Ivan's older sister. Hama returns in The Lost Age after Jupiter Lighthouse is cleared. She is a Jupiter Adept like her brother.
Justin and Megan - Two of the only remaining members of the Mercury Clan. Justin and Megan return briefly near the end of The Lost Age. Both are Mercury Adepts.
Kay - Garet's older sister. Kay returns briefly in the ending sequence of The Lost Age. Her element is never revealed, but her red hair and relation to Garet may be a sign that she is a Mars Adept.
Kyle - Isaac's father and Dora's husband. Presumed dead early in Golden Sun, Kyle returns near the end of The Lost Age. He is a Venus Adept.
Nyunpa - The head monk of Fuchin Temple. His element, and whether he is a true adept at all is unknown, though his powers are similar to that of Jupiter Adepts.
 In The Lost Age
Ahri - A baby in Contigo, she appears to be a Jupiter Adept.
Akafubu - Kibombo's new witch doctor. Akafubu is presumed to be a Mars Adept; it is revealed that the witch doctor's magic has a deep connection to Magma Rock.
Conservato - The leader of Lemuria's senate. Like all Lemurians, Conservato is a Mercury Adept.
Hydros - The king of Lemuria. Like all Lemurians, Hydros is a Mercury Adept.
Kushinada - Susa's fiance and a close friend of Uzume. Like them, Kushinada is assumed to be a Venus Adept because of her proximity to Gaia Rock.
Maha - The leader of Garoh. Like all residents of Garoh, Maha is a Jupiter Adept.
Poi - The head monk of Kandorean Temple. Similarly to Nyunpa, his element, or whether he is a true adept at all is unknown, though his spiritual powers are also similar to Jupiter Adepts.
Puelle - The mayor of Prox. Like all Proxians, Puelle is a Mars Adept.
Susa - Uzume's younger brother. Like his sister and Kushinada, Susa is assumed to be a Venus Adept because of his proximity to Gaia Rock.
Uzume - Izumo's leader and Susa's older sister. Like her brother and Kushinada, Uzume is assumed to be a Venus Adept because of her proximity to Gaia Rock.
 In Dark Dawn
Nowell - Daughter to Mia, sister of Rief and student of Kraden, this Mercury Adept fell in love with Piers and is now traveling with him.
Nyunpa - Makes a minor return from Golden Sun.
Volechek - Sveta's brother and king of Morgal. His element is never stated but his relationship to Sveta and his elemental statistics indicate a Jupiter alignment.
Tret - A returning character from Golden Sun. He is sought out by Matthew's party for adivce.
Laurel - A returning character from Golden Sun. She meets with Matthew's party, where she gives important advice regarding their quest.
Susa - A returning character from The Lost Age. He is king of Yamata and father to Himi and Takeru.
Kushinada - A returning character from The Lost Age. She is the queen of Yamata and mother to Himi and Takeru.
Uzume - A returning character from The Lost Age.
Takeru - The prince of Yamata and brother to Himi. He is not seen in game, but is mentioned to have gone on a quest to save Isaac.