Penguin Random House: The Best Sci-Fi Books of All Time

According to Penguin Random House:
A while ago, we came up with a list of the Best Fantasy Novels of All Time. Now we're doing the same with science fiction! Some of these are classic tales you will surely know, but others are excellent works of science fiction that may have been flying under the radar. So, dear readers, as you make your way down the list, congratulate yourselves on the books you've read and add the unfamiliar ones to your TBR list. Note: This list is organized alphabetically.