Sequels are a risky business. When they're done right, you get 'The Godfather Part II,''The Empire Strikes Back' and 'Aliens,' movies that many will argue surpass the seminal works that precede them.

When they're done wrong? You get the kind of movies that populate this list.

From the unnecessary to the ill-advised to the downright insulting, we present our picks for the Top 10 Worst Sequels (and Prequels) of 2009, where serial killers are slumming it with giant robots and your retinas will be fried by superfluous special effects. Read on ... if you dare.