It's a tough list to assemble, and sure to provoke some controversy, but we at SCI FI have come up with a list of 20 authors who helped make science fiction (and of course fantasy, horror etc.) the genres they are today. Plenty of big names didn't quite make the cut, there was a lot of chin-stroking and second thoughts, but we think you'll agree we've settled on a pretty potent gang of wordsmiths in the end.

This time around, we came with the names here in the office, but for future Top 20s, we will be getting you involved, so look out for your chance to cast a vote!

Just like our Top 20 Sexiest Men In Sci-Fi, we'll be updating this feature daily, culminating with our number 1 on Friday. Make sure you stay tuned, and click here to start with number 20!