Record label
In spite of the fact that both parties need each other to survive, the relationship between record labels and artists can, at times, be a difficult one.  Many artists have had albums changed or censored in some way by the labels before they are released—songs being edited, artwork or titles being changed, etc.  Record labels generally do this because they believe that the album will sell better if the changes are made.  Often the record label's decisions are correct ones from a commercial perspective, but this typically frustrates the artist who feels that their artwork is being destroyed.