Before CGI, we had to use a little imagination! Welcome to WatchMojo, and today we’re counting down our picks for incredible practical Effects from pre-2000s films that are still impressive today.

You don't need computers to create awful special Effects! For this list, we’ll be looking at visual Effects that were meant to be treated seriously, but look so ridiculous that we can’t help but giggle or groan.

If these videos prove anything, it's that CGI changes everything! For this list, we’ll be looking at some scenes from well-known films and comparing them to what they looked like before special Effects were added.

No computers needed here! For this list, we’ll be looking at the best, most believable or iconic examples of practical Effects found within horror movies.

TV CGI can often be a bit wonky, but these shows took it to another level of bad! For this list, we’ll be looking at the lowest points of computerized special Effects shown on television, though we won't be including TV movies on our list.

These terrible CGI movie Effects will leave you shaking your head in disbelief. For this list, we’ll be looking at the most embarrassing and unconvincing special Effects found in comic book movies.

Special Effects can look incredible...when done right. For this list, we're looking at the compositing shots in films that looked embarrassing instead of impressive.

These Effects were super-duds. For this list, we’ll be looking at just plain bad instances of CGI that can be found in major superhero films.

These special Effects are scary. Scary bad, that is. For this list, we’ll be looking at special Effects from popular horror movies that look less than optimal these days.

Sometimes movies are like sausages, in that it's better not to see them being made. For this list, we’ll be looking at behind-the-scenes peeks that showcase the mundane and often hilarious reality behind extravagant visual Effects.

These Effects are laughable. For this list, we’ll be looking at respectable attempts at big screen computer-generated imagery that utterly failed and remained unconvincing.

Nothing ruins a fantastic scene faster than awful visuals. For this list, we’ll be looking at times where bad special Effects distracted audiences from great scenes.

Why accept computer-generated imagery when you can have the real thing? For this list, we’re looking at scenes from films that feature heavy practical Effects work, with special attention going to the ones that are the most unbelievable.

You'll have to see it to believe it! For this list, we're looking at the top 20 actors recreated with special Effects.

Not even big budgets can save these movies from rotten special Effects. For this list, we're looking at the compositing shots in films released after the 1980s that looked embarrassing instead of impressive. We're basing our picks on a mix of poor blending, cartoony looks and the comedy or cringe that arises as a result of these poor Effects. Though the films we mention are not necessarily terrible, we're excluding the poorly financed world of indie flicks and b-movies no matter how egregious their contributions may be. Our countdown includes films such as "Speed Racer" (2008), "The Last Airbender" (2010) & "X-Men Origins: Wolverine" (2009). Which movie do YOU think has the worst blue/green-screen Effects? Let us know in the comments!