1. Jerry, Larry, Garry, Terry, Barry, Parks and Rec
    Not until season 4 does Jerry reveal his real name is Garry. A superior called him Jerry once and he thought it would be too rude to correct him. By the end of the series though,after many different rhyming names, his coworkers switch his name to Garry thinking they are keeping the joke alive.
  2. Donald to Jared, Silicon Valley
    Much like the above, Donald was called Jared his first day by Gavin Belson. And being the person he is, he found it easier to change his name rather than correct his boss.
  3. Celine to Chair, Another Period
    When Celine comes to the house as a servant, she's told her name sounds like a rich person's and that she is now called Chair.
  4. Eleanor to Fake Eleanor, The Good Place
    Eleanor is a bad person mistaken for a good person with the same name and sent to the Good Place after she dies. Once this mistake has been revealed and the Real Eleanor joins them, she becomes Fake Eleanor.
  5. Phil Miller to Tandy, the Last Man on Earth
    Even though there are only 7 known people alive in this world, two of them have the name Phil Miller. It's decided that the original Phil Miller will go by his middle name, Tandy. And even after Phil Miller is gone he continues to be called Tandy.
  6. Danny (30 Rock) — named Danny by Jack Donaghy, because there couldn't be two Jacks in the office
    Suggested by   @oholivia
  7. Haley James - Tutor Girl (One Tree Hill)
    Suggested by   @kate81
  8. Chandler "The Dropper" (FRIENDS)
    Suggested by   @kate81
  9. John James Preston was named Mr. Big by Carrie on Sex and the City
    Suggested by   @okayerin
  10. Scrubs is actually loaded with examples of these (Snoop Dogg Doctor, Colonel Doctor, Beardface, Lavernagain) but it always amused me that no one seemed to know Janitor's actual name nor did they care.
    Suggested by   @slicedbreadtime
  11. Charles Minor changes Erin's name from Kelly to Erin in The Office!
    Suggested by   @celestial