* William Hung: A contestant on the third season of American Idol, Hung became known for his off-key renditions of popular songs, despite a lack of vocal talent.
* Rebecca Black: A young singer-songwriter who rose to fame in 2011 for her song "Friday," which drew widespread criticism for its poor lyrics and simplistic production.
* Ashlee Simpson: Simpson's performance on the American television program "Saturday Night Live" in 2004 is often cited as one of the worst live singing performances in history. She appeared to lip sync while her pre-recorded vocals played, but when the backing track skipped, her live voice could be heard and revealed her inability to sing on key.
* Kesha: Kesha's vocal abilities have been criticized for being weak and lacking technique, particularly on her earlier songs such as "Tik Tok" and "We R Who We R."
* Britney Spears: Spears has also been criticized for her vocal abilities, particularly in her later career, with some critics arguing that her voice has become strained and pitchy.
Again, it is important to note that these are subjective opinions, and there are many other singers who have been criticized for their vocal skills. It is ultimately up to each individual to decide who they believe is the worst singer in the world.