Full details at the link, but the quick version is as follows:

If an author is not present, that's likely because official sales figures have not been released yet. Brandon Sanderson and Patrick Rothfuss, for example, should definitely be on here but as they have no official figures, I can't place them. That's also true for older authors like Arthur C. Clarke and Philip K. Dick.

1) J.K. Rowling (c. 450 million)
2) Stephen King (c. 350 million)
[Dean Koontz (c. 350 million)]
3) JRR Tolkien (c. 300 million)
[Michael Crichton (200 million)]
4) CS Lewis (120 million+)
5) Stephanie Meyer (116 million)
6) Sir Arthur C. Clarke (100 million+)
7) Anne Rice (100 million)
8 ) Robert Jordan ( 80 million+)
9) Sir Terry Pratchett (75 million+)
10 ) Richard Adams (50 million+)
11) Suzanne Collins (50 million+)
12) Christopher Paolini (39 million)
13) Michael Ende (35 million)
14) Stanislaw Lem (30 million+)
15) R.A. Salvatore (30 million+)
16) Kaoru Kurimoto (28 million)
17) Terry Brooks (26.5 million)
18 ) George Orwell (25 million+)
19) Terry Goodkind (25 million+)
20 ) George R.R. Martin (25 million+)
21) Cassandra Clare (24 million)
22) Kevin J. Anderson (23 million)
23) Eoin Colfer (21 million)
24) Isaac Asimov (20 million+)
25) Margaret Weis & Tracy Hickman (c. 20 million)
26) Brian Jacques (c. 20 million)
27) Kazumasa Hirai (c. 20 million)
28 ) Charlaine Harris (c. 20 million)
29) Raymond E. Feist (20 million+)
30 ) Michael Moorcock (20 million)
31) Frank Herbert (18 million)
32) Hideyuki Kikuchi (18 million)
33) Diana Gabaldon (17 million)
34) Douglas Adams (16 million)
35) Rick Riordan (15 million)
36) Philip Pullman (15 million)
37) Yoshiki Tanaka (15 million)
38 ) Timothy Zahn (15 million)
39) Robert Heinlein (11.5 million)
40 ) Stephen Donaldson (10 million)
41) Neil Gaiman (10 million + )
42) Alice Sebold (10 million+)
43) Madeline L'Engle (10 million+)
44) Ray Bradbury ( 8 million+)
45) David Weber (7 million)
46) Laurell K. Hamilton (6 million+)
47) Jim Butcher (6 million+)
48 ) L. Frank Baum (5 million+)
49) Frank Schatzing (4.2 million+)
50 ) David Drake (4 million)
51) Ursula K. Le Guin (3 million+)
52) Guy Gavriel Kay (3 million)
53) John Ringo (3 million)
54) Joe Abercrombie (3 million)
55) Margaret Atwood (3 million+)
56) Robert Silverberg (3 million+)
57) Eric Flint (3 million)
58 ) Harry Turtledove (2.5 million)
59) Audrey Niffenegger (2.5 million+)
60 ) Max Brooks (2.4 million+)
61) Orson Scott Card (2 million+)
62) Sergei Lukyanenko (2 million+)
63) Hans Dominik (2 million+)
64) Peter F. Hamilton (2 million+)
65) Brent Weeks (2 million)
66) Andrzej Sapkowski (2 million+)
67) Lois McMaster Bujold (2 million)
68 ) Susanna Clarke (1.5 million+)
69) Dan Abnett (1.2 million+)
70 ) Naomi Novik (1.2 million+)
71) Anne McCaffrey (1 million+)
72) Robin Hobb (1 million+)
73) David Gemmell (1 million+)
74) Steven Erikson (1 million+)
75) Alastair Reynolds (1 million+)
76) Trudi Canavan (1 million+)
77) Chris Wooding (750,000+)
78 ) Hugh Howey (500,000+)
79) Alison Croggon (500,000+)
80 ) Gail Carriger (400,000+)
81) Lynn Flewelling (350,000)
82) Peter V. Brett (310,000+)
83) Mark Lawrence (250,000+)
84) Michael J. Sullivan (250,000+)
85) Karen Miller (250,000+)
86) Scott Lynch (145,000+)
87) R. Scott Bakker (125,000+)
88 ) Elizabeth Moon (100,000+)
89) Gail Z. Martin (100,000+)