Who called William an upstart crow and why?

Robert Greene, a contemporary playwright, referred to William Shakespeare as an "upstart crow" in a 1592 pamphlet titled "Groats-Worth of Wit." Greene's comment was a critique of Shakespeare's rising fame and success as a playwright, suggesting that he was an ambitious newcomer trying to elevate himself above established writers. The term "upstart" implies someone who has risen quickly in status, while "crow" suggests a lack of sophistication or refinement, highlighting Greene's disdain for Shakespeare's rapid ascent in the competitive theatrical world.