In Hawaiian mythology, an ʻaumakua (//; often spelled aumakua, plural, 'aumākua) is a personal or family god that originated as a deified ancestor, and which takes on physical forms such as spirit vehicles. An 'aumakua may manifest as a shark, owl, bird, octopus, or inanimate objects such as plants or rocks. The word ʻaumakua means ancestor gods and is derived from the Hawaiian words au which means period of time or era, and makua meaning parent, parent generation, or ancestor. Hawaiians believed that deceased family members would transform into ʻaumakua and watch over their descendants with a loving concern for them while also being the judge and jury of their actions. 
ʻAumakua were believed to watch over their families and hear their words, give them strength and guidance, warn them of misfortune or danger, give punishments to wrong-doers while also rewarding worthy people with prosperity in the after life, and pass on prayers from the living to the akua (gods).
Hawaiian-born actor Jason Momoa has a halfsleeve tattoo on his left forearm that is a tribute to his family god, or aumakua, which is a shark. Some families had many ʻaumākua. Mary Kawena Pukui's family had at least fifty known ʻaumākua.
Roles of ʻAumākua
ʻAumakua could give warnings of coming misfortune or danger, punishments, and guidance to their respective ʻohana (families). ʻAumakua relayed these messages to family members through hōʻike a ka pō (revelation in the night, dreams), visions, or physical manifestations. Hawaiians also believed that “just the nagging feeling that something is wrong” was a message sent from their ʻaumakua.
ʻAumakua were also protectors of their families. An example of this comes from the Puna district on Hawaiʻi island which was shared with anthropologist Martha Beckwith: “...this one family… had a supernatural helper or aumakua who appeared in the form of a particular shark. When any of the family go fishing, the shark appears. The aumakua obeys the voice of man. Name the fish you want and it will bring it. This family can never be drowned. If there is a storm and the boat capsizes, the shark appears and the men ride on its back.” 
As protectors, ʻaumakua could also give mental or physical strength to ʻohana members who were in need of help but could not help themselves, primarily the keiki (children), the sick, and the elderly.
ʻAumakua could also bring punishment to families who offended or displeased them. These offenses included behavior like greed, dishonesty, and theft, breaking ʻai kapu (link to ʻai kapu article), bathing in pools that were kapu (taboo), and eating the physical form of ones ʻaumakua. Punishments were often illnesses in the form of “diagnostic clues”, so a thief would develop a swollen hand or a sore foot would trouble a trespasser until they made restitution.
ʻAumakua also acted as judge and jury after a person's death. They had the power to punish or reward the personʻs spirit depending on whether or not that person lived a righteous life, or even send the spirit back to the body if it left the body prematurely in “apparent deaths”. 
ʻAumākua could appear as:
- ʻalalā - crow
- manō - shark
- pueo - a species of short-eared owl
- heʻe - octopus
- mea kanu - plant
- pōhaku - rock
- mo'o - lizard
- Moa wahine - Mud hen
- Puhi - Eel
- ʻIole liʻiliʻi - Small field mice
- Peʻelua - Caterpillars
ʻAumakua were able to take on Kino lau (many bodies, many forms) which means that they could change back and forth from “invisible people'' (poʻe or ka pō), animals, plants, and minerals. ʻAumakua as animals could also inhabit plants that had similar characteristics or visual resemblance to that animal. For example, ʻaumakua as mackerel (ʻōpelu) were also associated with the lobelia plant (also called ʻōpleu) whose leaves are a similar shape and color as the fish.
- The 2016 Nintendo video games Pokémon Sun and Pokémon Moon, which are set in a fictional archipelago inspired by the real-world location of Hawaii, make reference to various aspects of Hawaiian culture, including the 'aumakua. Tapu Koko is called the guardian deity of Melemele Island and has a mask-like shell that looks like a stylized rooster head.
- In the 2016 Disney animated film Moana, the concept of the 'aumakua is an inspiration for Tala's transformation into a manta ray; the Aumakua is referenced by name in pre-production artwork.
- In "Ka laina ma ke one" ("Line in the Sand"), a seventh season episode of the U.S. television series Hawaii Five-O, Kono Kalakaua mentions that her family's aumakua is the manō, which motivates her to protect them.
- Barrow, Leonard J. (June 1999). "'Aumakua (Guardian Ancestors) in the Context of Contemporary Hawaiian Religious Beliefs". Rapa Nui Journal: Journal of the Easter Island Foundation. Archived from the original on October 31, 2019. Retrieved March 10, 2021.
- Silva, Noenoe (2009-01-12). "Nānā I Ke Kumu: Look to the Source". Te Kaharoa. 2 (1). doi:10.24135/tekaharoa.v2i1.125. ISSN 1178-6035.
- Friedman, Megan (2018-07-23). "Are Jason Momoa's 'Aquaman' Tattoos Actually Real?". Men's Health. Retrieved 2019-08-24.
- Pukui, Mary Kawena; E. W. Haertig, Catharine A. Lee (June 1983). Nana I Ke Kumu (Look to the Source). Hui Hanai. ISBN 978-0-9616738-0-2.
- BECKWITH, MARTHA WARREN (1917-10-12). "HAWAIIAN SHARK AUMAKUA". American Anthropologist. 19 (4): 503–517. doi:10.1525/aa.1917.19.4.02a00060. ISSN 0002-7294.
- Banko, Paul C.; Donna L. Ball; Winston E. Banko (2002). "Hawaiian Crow (Corvus hawaiiensis)". In A. Poole (ed.). The Birds of North America Online. Cornell Lab of Ornithology. Archived from the original on August 13, 2009. Retrieved 2009-03-20.
- Clair, Robert St. (April 1973). ": Hawaiian-Dictionary: Hawaiian-English English-Hawaiian . Mary Kawena Pukui, Samuel L. Elbert". American Anthropologist. 75 (2): 503–504. doi:10.1525/aa.1973.75.2.02a01020. ISSN 0002-7294.
- "Tapu Koko". Pokemon Sun-Pokemon Moon. Nintendo. Retrieved 14 June 2017.
- "Ryan Lang's Portfolio - Moana". Ryan Lang's Portfolio.
- "Hawaii's Spirit Guardians" Article by Rita Goldman in Maui No Ka 'Oi Magazine, Vol.14 No. 6 Nov 2010.
- "The Meaning Behind Hawaiian Symbols: The Guardian Spirits" Article by OluKai, The Meaning Behind Hawaiian Symbols, 3 Nov 2014.