I came across an old post from 5 years ago by @Werthead listing bestselling science fiction and fantasy authors by sales. I think he's updated the list since then - however, after a recent thread on literary works, I thought it might be interesting to see how many of the following authors people have read at least one novel by.
I'll repost the list here for reference:
1) J.K Rowling (c. 450 million)
2) Stephen King (c. 350 million)
3) JRR Tolkien (c. 300 million)
4) CS Lewis (120 million+)
5) Stephanie Meyer (116 million)
6) Anne Rice (100 million)
7) Robert Jordan (80 million+)
8) Sir Terry Pratchett (65 million+)
9) Richard Adams (50 million+)
10) Suzanne Collins (50 million+)
11) Christopher Paolini (33 million)
12) R.A. Salvatore (30 million+)
13) Kaoru Kurimoto (28 million)
14) George Orwell (25 million+)
15) Terry Goodkind (25 million)
16) Cassandra Clare (24 million)
17) Terry Brooks (21 million+)
18) Eoin Colfer (21 million)
19) George R.R. Martin (20 million+)
20) Isaac Asimov (20 million+)
21) Margaret Weis & Tracy Hickman (c. 20 million)
22) Brian Jacquies (c. 20 million)
23) Kazumasa Hirai (c. 20 million)
24) Charlaine Harris (c. 20 million)
25) Frank Herbert (18 million)
26) Hideyuki Kikuchi (18 million)
27) Diana Gabaldon (17 million)
28) Douglas Adams (16 million)
29) Kevin J. Anderson (16 million)
30) Raymond E. Feist (15 million+)
31) Rick Riordan (15 million)
32) Philip Pullman (15 million)
33) Yoshiki Tanaka (15 million)
34) Stephen Donaldson (10 million)
35) Neil Gaiman (10 million + )
36) Alice Sebold (10 million+)
37) Madeline L'Engle (10 million+)
38) Timothy Zahn (8 million)
39) Laurell K. Hamilton (6 million+)
40) Frank L. Baum (5 million+)
41) Guy Gavriel Kay (3 million)
42) John Ringo (3 million)
43) Joe Abercrombie (3 million)
44) Harry Turtledove (2.5 million)
45) Peter F. Hamilton (2 million+)
46) Dan Abnett (1.2 million+)
47) Robin Hobb (1 million+)
48) David Gemmell (1 million+)
49) Steven Erikson (1 million+)
50) Trudi Canavant (1 million+)
51) Chris Wooding (450,000+)
52) R. Scott Bakker (125,000+)
I think I only got up to 25 that I finished reading, but I'm sure that score will be easily beaten here.
I'll repost the list here for reference:
1) J.K Rowling (c. 450 million)
2) Stephen King (c. 350 million)
3) JRR Tolkien (c. 300 million)
4) CS Lewis (120 million+)
5) Stephanie Meyer (116 million)
6) Anne Rice (100 million)
7) Robert Jordan (80 million+)
8) Sir Terry Pratchett (65 million+)
9) Richard Adams (50 million+)
10) Suzanne Collins (50 million+)
11) Christopher Paolini (33 million)
12) R.A. Salvatore (30 million+)
13) Kaoru Kurimoto (28 million)
14) George Orwell (25 million+)
15) Terry Goodkind (25 million)
16) Cassandra Clare (24 million)
17) Terry Brooks (21 million+)
18) Eoin Colfer (21 million)
19) George R.R. Martin (20 million+)
20) Isaac Asimov (20 million+)
21) Margaret Weis & Tracy Hickman (c. 20 million)
22) Brian Jacquies (c. 20 million)
23) Kazumasa Hirai (c. 20 million)
24) Charlaine Harris (c. 20 million)
25) Frank Herbert (18 million)
26) Hideyuki Kikuchi (18 million)
27) Diana Gabaldon (17 million)
28) Douglas Adams (16 million)
29) Kevin J. Anderson (16 million)
30) Raymond E. Feist (15 million+)
31) Rick Riordan (15 million)
32) Philip Pullman (15 million)
33) Yoshiki Tanaka (15 million)
34) Stephen Donaldson (10 million)
35) Neil Gaiman (10 million + )
36) Alice Sebold (10 million+)
37) Madeline L'Engle (10 million+)
38) Timothy Zahn (8 million)
39) Laurell K. Hamilton (6 million+)
40) Frank L. Baum (5 million+)
41) Guy Gavriel Kay (3 million)
42) John Ringo (3 million)
43) Joe Abercrombie (3 million)
44) Harry Turtledove (2.5 million)
45) Peter F. Hamilton (2 million+)
46) Dan Abnett (1.2 million+)
47) Robin Hobb (1 million+)
48) David Gemmell (1 million+)
49) Steven Erikson (1 million+)
50) Trudi Canavant (1 million+)
51) Chris Wooding (450,000+)
52) R. Scott Bakker (125,000+)
I think I only got up to 25 that I finished reading, but I'm sure that score will be easily beaten here.