Carl Fletcher (portrayed by Josh Stamberg) is a tenant in Sarah Braverman's building. He is also Sarah's ex-boyfriend, as well as a successful doctor.
Carl first seen as one of Sarah Braverman's building, which she supervises. He is a successful doctor, but is known as a "playboy," as he always brings home young girls to his apartment. He and Sarah often bump into each other within the building, but other than that, don't know each other too well.
Soon, Carl and Sarah spend a night in his apartment. When the power goes out, Carl kisses Sarah in the dark, and the two sleep together. The next day, Sarah tells him that they can't do that again, and he subsequently agrees with her.
An unknown amount of time later, Carl asks Sarah to attend a charity event with him. Even though she is reluctant, she eventually agrees when he assures her that it will be just as friends. At the event, Sarah discovers that the event is actually honoring Carl since he is a doctor who helps disabled and poor children. This is when Sarah begins to see a different side of Carl.
Sarah and Carl become friends, and he encourages her to dream big in her workplace. He books her an interview with SurfSport, a popular company for which she would take advertising pictures. She gets the job, beating out Hank Rizzoli, who accuses her of only getting the job because she is dating Carl. Sarah refuses to believe that, as she and Carl are just friends.
After Sarah gets the job, she and Carl become closer, as they go to many dinners together. At one dinner, he admits to her that she is beautiful and he may be "falling for her." They begin dating and sleeping together again, and all is going well. One morning, Carl asks her to go to Africa with him for a one-week business trip. She agrees to go until Hank tells her that this is just like her: to drop everything just to be with a guy. She realizes Hank is right and decides not to go, breaking up with Carl in the process. Carl goes to Africa after the breakup.