Since it debuted in 1999, Law & Order: SVU has been celebrated as one of TV's finest acted series. The crime drama is known for its outstanding main cast, but SVU has also had many memorable guest stars over the years. Frequently, these performers played criminals who were apprehended by the unit, but sometimes they assisted investigations too. In this gallery, we take a look at the very best SVU guest stars — a list that includes more than a few A-list names!RELATED: Law & Order: SVU - See the Season 1 Cast!