Belly Buttonless

It's a fact of life—no matter how placental a mammal is, clones don't have belly buttons. It's a common plot device used to distinguish those inferior, artificially created creatures from natural, unique human beings. Makes those knowledgeable of human physiology wonder just how these people developed, not having ever been attached to placentas before.

Natural clones such as identical twins don't count. They get to keep their navels.

Justified if the process for creating the beings somehow has nothing to do with fetal development, or if the species isn't even placental in the first place. It is common in magical constructs such as homunculi too, and of artificial beings in general.

Anime and Manga

 * Youkai in Tokimeki Mononoke Jogakkou lack bellybuttons, so Arare has to keep hers hidden to avoid being found out as a human.
 * An early chapter of Doctor Slump has Robot Girl Arale worried because she lacks a navel and her classmates find that weird, so she wants one. Except her creator Senbei thinks she wants something a bit lower, which he's never seen because of Japanese censorship. Hilarity Ensues.

Film

 * Rocky from The Rocky Horror Picture Show has no navel.

Literature

 * In the Virgin New Adventures, Time Lords are constructed by machines and so lack navels. The Doctor is an exception.
 * Dejah Thoris from John Carter of Mars, being Martian, an egg-laying species, has no bellybutton.
 * In The Barsoom Project, Martin Qaterliaraq is an Inuit shaman character in the Fimbulwinter Game. His lack of a navel is an early indication that his character was crafted from molded lava by the Raven, not born.

Live-Action TV

 * The in-vitroes from Space: Above and Beyond lacked standard belly-buttons. Instead, they had nipple-like bumps on the back of their necks from there the artificial placentas attached to them in the womb-tanks.
 * On Mork and Mindy after M&M got married and had sex for the first time, Mork proved he had laid an egg by showing his navel - since he's an Orkan he doesn't have one from the natural gestation process. Other than all the times he'd shown his belly before that episode and we'd seen it.
 * In The Brittas Empire, Gordon doesn't have a belly button after some plastic surgery following his return from the dead (It Makes Sense in Context, sorta)
 * Luke Smith from The Sarah Jane Adventures also lacks a navel, due to being created by the Bane.
 * A rather bizarre and Fridge Logic-filled example: in Sorry's It's a Wonderful Plot episode, Timothy loses his belly button because "he was never born".
 * The Charmed episode "Size Matters" has a demonic construct who demonstrates to Paige that he's not like ordinary people by showing her that he lacks a belly button.
 * On the show Kyle XY, the fact that he has no belly button was what alerted the people who found him that he was not quite normal.
 * Clone from the BBC 3 series Clone, has this. Or doesn't have this. YOU KNOW.
 * Averted with a vengeance by Gene Roddenberry in his 1973 post-Star Trek pilot film, Genesis II (and its Retool, 1974's Planet Earth). The evil Tyranians had a double circulatory system and two navels -- an often plot-critical detail implemented because Roddenberry had tired of endless memos from NBC's Broadcast Standards department insisting that all navels be hidden on Star Trek.

Web Comics

 * In Unsounded, Sette has no belly button (in addition to her Barbie Doll Anatomy, which Word of God says is her actual anatomy).

Western Animation

 * An episode of The Simpsons involves Homer's life being invaded by an army of clones of himself. The clones, predictably enough, lack belly buttons.
 * Strong Sad from Homestar Runner has a belly button... ...but it was created by Strong Bad's power drill.

Real Life
"Q: If you go to Heaven and look for Adam and Eve, how will you know which two people are them? A: They're the only two without belly buttons."
 * There is an old joke:


 * Czech Model Karolina Kurkova (somewhat) famously has no navel, due to surgery she had as an infant. Her lack of a natural belly-button has given rise to accusations of over-airbrushing when she appears in photo spreads. Ironically, this has caused some photo editors to Photoshop one onto her photos, in order to avoid accusations of over photo-editing!
 * Some laparoscopic surgical procedures use the belly button as a point of entry to keep any resulting scars from being conspicuous. Later overgrowth of skin as the entry-point heals may cause the patient's navel to shrink to almost nothing.
 * Likewise, surgical repair of an umbilical hernia, or a rare congenital defect in which an infant's belly wall is incomplete at birth, may require the abdomen to be sutured shut, leaving a scar rather than a navel.
 * Alfred Hitchcock had no navel due to surgery.