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 ) Sir Terry Pratchett ( 85 million+)
9) Robert Jordan ( 80 million+)
10 ) James Herbert (54 million+)
11) Richard Adams (50 million+)
12) Suzanne Collins (50 million+)
[Dennis Wheatley (50 million)]
[Morgan Llywelyn (40 million)]
13) Christopher Paolini (39 million)
14) Michael Ende (35 million)
15) Stanislaw Lem (30 million+)
16) R.A. Salvatore (30 million+)
17) Charlaine Harris (30 million+)
18 ) George R.R. Martin (28 million+)
19) Kaoru Kurimoto (28 million)
20 ) Terry Brooks (26.5 million)
21) George Orwell (25 million+)
22) Terry Goodkind (25 million+)
23) Diana Gabaldon (25 million)
24) Cassandra Clare (24 million)
25) Kevin J. Anderson (23 million)
26) Eoin Colfer (21 million)
27) Isaac Asimov (20 million+)
28 ) Margaret Weis & Tracy Hickman (c. 20 million)
29) Brian Jacques (c. 20 million)
30 ) Kazumasa Hirai (c. 20 million)
31) Raymond E. Feist (20 million+)
32) Michael Moorcock (20 million)
33) Frank Herbert (18 million)
34) Hideyuki Kikuchi (18 million)
35) Tad Williams (17 million)
36) Douglas Adams (16 million)
37) Rick Riordan (15 million)
38 ) Philip Pullman (15 million)
39) Yoshiki Tanaka (15 million)
40 ) Timothy Zahn (15 million)
41) Robert Heinlein (11.5 million)
42) Diana Wynne Jones (10 million+)
43) Robert E. Howard (10 million+)
44) Stephen Donaldson (10 million)
45) Neil Gaiman (10 million + )
46) Alice Sebold (10 million+)
47) Madeline L'Engle (10 million+)
48 ) Chris Bunch (10 million+)
49) Allan Cole (10 million+)
50 ) Ray Bradbury million+)
51) David Weber (7 million)
52) Laurell K. Hamilton (6 million+)
53) Jim Butcher (6 million+)
54) L. Frank Baum (5 million+)
55) Garth Nix (5 million)
56) Frank Schatzing (4.2 million+)
57) Lian Hearn (4 million)
58 ) David Drake (4 million)
59) Veronica Roth (4 million)
60 ) Roger Zelazny (3.5 million+)
61) Ursula K. Le Guin (3 million+)
62) Guy Gavriel Kay (3 million)
63) John Ringo (3 million)
64) Joe Abercrombie (3 million)
65) Margaret Atwood (3 million+)
66) Robert Silverberg (3 million+)
67) Eric Flint (3 million)
68 ) Scott Westerfield (3 million+)
69) Harry Turtledove (2.5 million)
70 ) Audrey Niffenegger (2.5 million+)
71) Max Brooks (2.4 million+)
72) Susan Cooper (2 million+)
73) Orson Scott Card (2 million+)
74) Sergei Lukyanenko (2 million+)
75) Hans Dominik (2 million+)
76) Peter F. Hamilton (2 million+)
77) Brent Weeks (2 million)
78 ) Andrzej Sapkowski (2 million+)
79) Lois McMaster Bujold (2 million)
80 ) Katherine Kurtz (2 million)
81) Trudi Canavan (2 million+)
82) Stephen Lawhead (2 million+)
83) Robert Rankin (2 million+)
84) Maggie Stiefvater (2 million+)
85) Melanie Rawn (1.8 million+)
86) Jennifer Roberson (1.7 million)
87) Susanna Clarke (1.5 million+)
88 ) Dan Abnett (1.2 million+)
89) Naomi Novik (1.2 million+)
90 ) Ed Greenwood (1 million+)
91) L.E. Modesitt, Jr. (1 million+)
92) Connie Willis (1 million)
93) Sara Douglass (1 million)
94) Anne McCaffrey (1 million+)
95) Robin Hobb (1 million+)
96) David Gemmell (1 million+)
97) Steven Erikson (1 million+)
98 ) Alastair Reynolds (1 million+)
99) Ian Irvine (1 million+)
100 ) Richard A. Knaak (1 million+)
101) Katherine Kerr (1 million+)
102) Dave Duncan (1 million+)
103) Chris Wooding (750,000+)
104) Hugh Howey (500,000+)
105) Alison Croggon (500,000+)
106) Gail Carriger (400,000+)
107) Lynn Flewelling (350,000)
108 ) Peter V. Brett (310,000+)
109) Kate Elliott (300,000+)
110 ) Ernest Cline (300,000)
111) J.V. Jones (250,000+)
112) Mark Lawrence (250,000+)
113) Michael J. Sullivan (250,000+)
114) Karen Miller (250,000+)
115) Gail Z. Martin (180,000+)
116) Daniel H. Wilson (160,000+)
117) Scott Lynch (145,000+)
118 ) R. Scott Bakker (125,000+)
119) Glenda Larke (120,000+)
120 ) Elizabeth Moon (100,000+)