He's Hiding in Plain Sight
This theory is really out there. According to Reddit user ksendor, Dr. Manhattan could be on Earth, masquerading himself as Angela's husband, Cal. Perhaps longing for connection again, Manhattan transformed himself into another person, capable of emotion and love without the burdens of his powers. To support his theory, ksendor cites Cal's quick dismissal of Manhattan's supposed ability to change appearance, Laurie's apparent fascination and attraction to Cal, and, believe it or not, the knuckles of actor Yahya Abdul-Mateen II (who plays Cal). When compared to a screenshot of what appears to be Manhattan's hand and Yahya's fingers, kdsendor found striking similarities.