Doctor Manhattan's human disguise in Watchmen, Cal Abar (Yahya Abdul-Mateen II), could have actually been a real person whose body the superbeing took over. Watchmen episode 7, "An Almost Religious Awe", concluded with a surprising twist that Doctor Manhattan has been in plain sight all along as the unassuming husband of Detective Angela Abar AKA Sister Night (Regina King). Fans had come to accept Watchmen's constant explanation that the world's most powerful being has been living on Mars since 11/2/1985, so it was a genuine shock when Angela revealed that Cal was Manhattan the whole time.
Angela and Cal perpetuated an elaborate lie in order to live happily together as a couple in Tulsa, Oklahoma. Meanwhile, the rest of the world was completely unaware that Doctor Manhattan AKA Jon Osterman was actually back on Earth and thousands of people have spent years calling the blue demigod on Mars with prayers via Trieu Industries' Blue Booths. According to the Abars' deception, Cal suffered an accident in Saigon that caused total amnesia - but Cal actually wiped his own memory of being Manhattan, which was his idea. Cal/Manhattan and Angela then moved to Tulsa to start over; Angela became a masked Tulsa Police Detective (with a cover story of owning a bakery) while Cal stayed home to watch over the three kids they adopted after the White Night tragedy. It was a perfect ruse, but somehow, both Angela's grandfather Will Reeves AKA Hooded Justice (Louis Gosssett, Jr.) and the Seventh Kavalry/Cyclops white supremacist cult discovered Doctor Manhattan was secretly living in Tulsa.
But where did the physical body of "Cal Abar" come from? Watchmen's tie-in website Peteypedia furthers the mystery of Doctor Manhattan's human disguise by uncovering Cal's medical records from his 'accident' in Saigon. Despite Angela reminding Cal that "there was no accident, it was a lie" before she released Doctor Manhattan from his flesh-and-blood shell, there is an actual hospital chart from when Cal was admitted into Rampart Memorial Hospital in Saigon on 12/23/09, where he was treated by Dr. K. Brackett. Even more curious is the fact that Cal was admitted under the name "Cal Jelani" (which hasn't been mentioned in Watchmen), not Abar, which seems to be the surname Angela adopted after the death of her family. Further, the sheer amount of background details in Cal Jelani's medical chart indicates that Cal was a real person who Doctor Manhattan placed his consciousness into in the form of his icon, the hydrogen atom, which was buried in Cal's forehead (and Angela later retrieved to revive Doctor Manhattan's true blue form).
According to Cal's intake form, he was born in Philadelphia on 11/22/76, he worked in construction for Pyramid Global but was unemployed and without insurance, and Cal had arrived in Saigon a month before his 'accident'. Supposedly, Angela found him wandering Bom Laird Plaza in a "confused state". There was a "minor contusion" on his forehead (from where Doctor Manhattan's symbol was inserted) that vanished. The chart also lists Cal's family medical history (including that he is circumcised) and Dr. Beckett noted that Cal was particularly interested in a Doctor Manhattan bobblehead.
With so much medical background about Cal Jelani available, how could all of it have been faked? It's quite possible there really was a Cal Jelani (who may or may not have been in an accident in Saigon) and that Angela and Doctor Manhattan took over Cal's body for Jon Osterman to hide in. After all, Angela is only a cop and she wouldn't have the resources to fabricate a person's entire medical history to facilitate her big lie.
However, Doctor Manhattan's powers include creating nearly anything from matter so it's quite possible he built the body of Cal himself. If that's the case, a clue to how Cal has such a detailed fake medical history readily available could be who he worked for: Pyramid Global, one of the subsidiaries of Adrian Veidt (Jeremy Irons). It's possible Ozymandias himself helped fabricate "Cal" to help Doctor Manhattan live incognito as a 'normal man'. Hopefully, the answer to the mystery of where Cal Abar came from will be in Watchmen episode 8, "A God Walks Into A Bar".
Watchmen airs Sundays @ 9pm on HBO.