Due to the potent magic of the Genesis Spell, the Young Guardians cannot physically age past 18.
Wolverine's (Marvel Comics) regenerative abilities slow his aging dramatically, as he is over 100, yet still in his prime.
Sabretooth's (Marvel Comics) regenerative abilities slow his aging dramatically.
Mystique (Marvel Comics) uses her shapeshifting abilities to rejuvenate her cells, slowing her aging process.
Half-vampire Blade (Marvel Comics) has a much longer lifespan than a normal human.
The Flash's (DC Comics) differing metabolism slows his aging.
Pure-blood Saiyans, like Son Goku (Dragon Ball), have a much slower aging rate than earthlings and part-Saiyans.
Half-demon Inuyasha (InuYasha) has a longer lifespan than normal humans, living over 50 years without aging past his teenage appearance.
Though well over fifty years old, Laura Weathermill (Angel) has the appearance of a young woman.
Due to his time in the Lost Land, Turok's (Turok: Dinosaur Hunter) aging process has been greatly slowed.
Jenny Quantum (WildStorm/DC Comics) stopped aging once she reached adulthood.
Sir George (Ben 10) is well over a thousand years old.
Though chronologically in her late forties or early fifties, Miss Martian (Young Justice/DC Comics) is only sixteen by the Martian calendar.
Though chronologically over a hundred years old, Liara T'Soni (Mass Effect) is little more than a child by asari standards.
Though over a hundred years old, Saya Otonashi (Blood+) stopped aging when she was biologically 16.
Gabriel Van Helsing (Van Helsing) has apparently been alive since the first century, yet is still in his prime.
Perhaps as a result of being stranded in the Realm of Darkness for eleven years, Aqua (Kingdom Hearts) has not aged a day and still appears to be in her late teens or early twenties.
Thanks to the Infinity Formula, Nick Fury (Marvel Comics) remains in his prime despite chronologically being nearly 100 years old.
Though chronologically 19, Shelke (Dirge of Cerberus -Final Fantasy VII-) stopped aging at nine due to Deepground's experiments.
Olaf barely aged after he became the reincarnation of Baldr at his 21st birthday, he already has about 20 children and at least 4 grandchildren.
Though she has the appearance and personality of a young child, Nowi (Fire Emblem: Awakening) is over 1000 years old.
Despite having the appearance of a pre-teen girl, Rurumo (Majimoji Rurumo) spent over 60 years in the magic/witch world jail and is at least 150 years old.
Due to a contract with Shang Tsung, Erron Black (Mortal Kombat X) has slowed aging, still appearing in his prime despite being over 150 years old.
Sycorax (Doctor Who) live for 400 years
Zygons (Doctor Who) can seemingly live for centuries.
Tomiko Asahina (From the New World) has slowed her aging dramatically and lived for over 250 years by continually rejuvenating her telomeres
Despite her youthful appearance, Aqua (Di Gi Charat) is over 120 years old.
Though in her late thirties, Aya Brea's (Parasite Eve) aging process has been greatly slowed by the mitochondria in her cells, giving her the appearance of a woman in her early twenties.
Grandfather (Codename: Kids Next Door) has been alive ever since the 19th century in the exact same physical state, despite his aged appearance in the 21st century.
Like all dwarves, Romilda's (Outbreak Company) aging is static, meaning that her appearance will not change from childhood all the way until she dies, thus making it impossible to tell exactly how old she truly is.
All Ninetales (Pokemon) have a wondrous energy store in their nine tails that could keep them alive for 1,000 years