Users physical needs are greatly reduced or completely removed. These needs include air/breathing, sleep/rest, food, drink, bodily evacuations, shelter from environmental effects and their lack (heat/cold, dryness/wetness), etc. The user is also able to stay immobile without the normal effects this would have.
Due to the effects of yellow sun radiation, Superman (DC Comics) has no need for food or sleep, though he tends to eat and sleep out of habit.
As long as the Amazons (DC Comics) stay on Themyscira, they don't require food, water or any other form of nourishment to maintain their health and vitality.
Olympians (DC Comics)
Shinigami (Death Note) have no need to eat nor sleep, but do so to enjoy the sensation and laziness. They do, however, need to use the Death Note to extend their lifespan.
Artificial Humans (Dragon Ball) like #16, #17, and #18 have an infinite energy reservoir, and thus, no need to sleep or eat.
Namekians like Dende (Dragon Ball series) do not need food to survive; they can subsist solely on water.
Majin Buu (Dragon Ball series) has no need to breathe, sleep, or eat and has limitless stamina. While he does greatly enjoy eating, he only requires to hibernate on occasion.
Angels (Dragon Ball Super) do not need to sleep, eat, or breathe, and are effectively immortal.
Ultimate Mr. Fantastic's (Marvel Comics) organs have been replaced with a "bacterial stack"; as a result, he has no need for food, water, or even oxygen.
Hashirama Senju's DNA cells allowed Obito Uchiha (Naruto) to survive without food or water.
Zetsu (Naruto) are self-sustained, as Black Zetsu is an artificial human created from Kaguya's materialized will, while White Zetsu are mutated humans. Although, White Zetsu can devour corpses to dispose of evidence.
Because Timmy Taco wished that he and Sally Sandwich (Sweet Story) would be "married forever", it made it so that neither could ever die - including immunity to the effects of starvation or thirst - the wish making sure that their marriage does not end through death do [they] part.
Gems (Steven Universe) are an alien race of functionally-immortal polymorphic Gemstones. They do not need to eat, drink, sleep or breath, and can recede into their gems should their bodies be mortally wounded to heal.
Ultimate Kevin (Ben 10 Ultimate Alien)
Olympians (Marvel Comics)
Through methods not understood by other races, Reapers (Mass Effect) perpetually generate nigh-limitless amounts of energy, making a war of attrition against them impossible. A single Reaper can live for millions of years without needing any kind of fuel or sustenance.
As a human-vampire hybrid, Renesmee Cullen (Twilight) has a beating heart that pumps blood in her system, making her independent of blood.
When Vlad (Danny Phantom) went into space the second time he is shown to breathe in space without the use of an oxygen tank or a helmet, showing he is capable of surviving in low-pressure, low-temperature environments.
Due to Ban (Seven Deadly Sins) drinking the fountain of youth he does not need to eat or drink.