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 Philip K. Dick.

Authors listed in [] are writers who have mostly published non-SFF, and where it is impossible to extract their non-SFF sales from their SFF ones. Their total sales are listed for comparison purposes.

1) J.K. Rowling (c. 450 million)
2) Stephen King (c. 350 million)
3) JRR Tolkien (c. 300 million)
[Dean Koontz (c. 200 million)]
[Michael Crichton (200 million)]
4) Anne Rice (136 million)
5) CS Lewis (120 million+)
6) Stephanie Meyer (116 million)
7) Sir Arthur C. Clarke (100 million+)
8 ) Andre Norton (90 million+)
9) Sir Terry Pratchett ( 85 million+)
10 ) Robert Jordan ( 80 million+)
11) James Herbert (54 million+)
12) Richard Adams (50 million+)
13) Suzanne Collins (50 million+)
[Dennis Wheatley (50 million)]
[Jean M. Auel (45 million)]
[Morgan Llywelyn (40 million)]
14) Christopher Paolini (39 million)
15) Michael Ende (35 million)
16) Stanislaw Lem (30 million+)
17) R.A. Salvatore (30 million+)
18 ) Charlaine Harris (30 million+)
19) Sherrilyn Kenyon (30 million+)
20 ) Robert Heinelin (30 million+)
21) George R.R. Martin (28 million+)
22) Kaoru Kurimoto (28 million)
23) Terry Brooks (26.5 million)
24) George Orwell (25 million+)
25) Marion Zimmer Bradley (25 million+)
26) Darren Shan (25 million+)
27) Terry Goodkind (25 million+)
28 ) Diana Gabaldon (25 million)
29) Cassandra Clare (24 million)
30 ) Kevin J. Anderson (23 million)
31) Eoin Colfer (21 million)
32) Isaac Asimov (20 million+)
33) Margaret Weis (c. 20 million)
34) Tracy Hickman (c. 20 million)
35) Brian Jacques (c. 20 million)
36) Kazumasa Hirai (c. 20 million)
37) Raymond E. Feist (20 million+)
38 ) Michael Moorcock (20 million)
39) Mercedes Lackey (20 million)
40 ) Frank Herbert (18 million)
41) Hideyuki Kikuchi (18 million)
42) Anne McCaffrey (18 million+)
43) Tad Williams (17 million)
44) Larry Niven (17 million)
45) Douglas Adams (16 million)
46) Brandon Sanderson (15 million+)
47) Rick Riordan (15 million)
48 ) Philip Pullman (15 million)
49) Yoshiki Tanaka (15 million)
50 ) Timothy Zahn (15 million)
51) Diana Wynne Jones (10 million+)
52) Robert E. Howard (10 million+)
53) Stephen Donaldson (10 million)
54) Neil Gaiman (10 million + )
55) Alice Sebold (10 million+)
56) Madeline L'Engle (10 million+)
57) Jerry Pournell (10 million+)
58 ) Chris Bunch (10 million+)
59) Allan Cole (10 million+)
60 ) Peter Straub (10 million+)
61) Frederik Pohl (10 million+)
62) Cyril M. Kornbluth (10 million+)
63) David Eddings ( 8.5 million+)
64) Ray Bradbury ( 8 million+)
65) Christopher Golden ( 8 million+)
[Bernard Cornwell (7 million+)]
66) David Weber (7 million)
67) Orson Scott Card (7 million+)
68 ) William Gibson (6.5 million+)
69) Peter S. Beagle (6 million+)
70 ) Laurell K. Hamilton (6 million+)
71) Jim Butcher (6 million+)
72) L. Frank Baum (5 million+)
73) Daniel Keyes (5 million+)
74) Garth Nix (5 million)
75) Robert R. McCammon (5 million+)
76) Frank Schatzing (4.2 million+)
77) Fritz Leiber (4 million+)
78 ) Vonda N. McIntyre (4 million)
79) Lian Hearn (4 million)
80 ) David Drake (4 million)
81) Veronica Roth (4 million)
82) Roger Zelazny (3.5 million+)
83) Aaron Allston (3.3. million+)
84) Robert Harris (3 million+) (SF only)
85) Alan Dean Foster (3 million+)
86) Ursula K. Le Guin (3 million+)
87) Guy Gavriel Kay (3 million)
88 ) Lloyd Alexander (3 million)
89) Dan Abnett (3 million+)
90 ) John Ringo (3 million)
91) Joe Abercrombie (3 million)
92) Margaret Atwood (3 million+) (SF only)
93) Robert Silverberg (3 million+)
94) Eric Flint (3 million)
95) Scott Westerfield (3 million+)
96) Robert Asprin (3 million)
97) Rick Hautala (3 million+)
98 ) Brian Lumley (3 million+)
99) Harry Turtledove (2.5 million)
100 ) S.M. Stirling (2.5 million)
101) Audrey Niffenegger (2.5 million+)
102) Michelle Paver (2.5 million+)
103) Max Brooks (2.4 million+)
104) James Dashner (2.3 million+)
105) Susan Cooper (2 million+)
106) Sergei Lukyanenko (2 million+)
107) Hans Dominik (2 million+)
108 ) Peter F. Hamilton (2 million+)
109) Brent Weeks (2 million)
110 ) Andrzej Sapkowski (2 million+)
111) Lois McMaster Bujold (2 million)
112) Katherine Kurtz (2 million)
113) Trudi Canavan (2 million+)
114) Stephen Lawhead (2 million+)
115) Robert Rankin (2 million+)
116) Maggie Stiefvater (2 million+)
117) Gregory Benford (2 million+)
118 ) Greg Bear (2 million+)
119) Gordon R. Dickson (2 million+)
120 ) Jacqueline Carey (2 million+)
121) Piers Anthony (2 million+)
122) Melanie Rawn (1.8 million+)
123) Jennifer Roberson (1.7 million)
124) Elizabeth Moon (1.5 million+)
125) Deborah Harkness (1.5 million+)
126) Susanna Clarke (1.5 million+)
127) Markus Heitz (1.5 million+)
128 ) Seth Grahame-Smith (1.4 million+)
129) Dan Simmons (1.25 million+)
130 ) Stan Nicholls (1.25 million+)
131) Naomi Novik (1.2 million+)
132) Iain M. Banks (1.1 million+) (SF only)
133) Kelley Armstrong (1 million+)
134) Samuel R. Delany (1 million+)
135) Ed Greenwood (1 million+)
136) Paul S. Kemp (1 million+)
137) L.E. Modesitt, Jr. (1 million+)
138 ) Connie Willis (1 million)
139) Sara Douglass (1 million)
140 ) Robin Hobb (1 million+)
141) David Gemmell (1 million+)
142) Steven Erikson (1 million+)
143) Alastair Reynolds (1 million+)
144) Ian Irvine (1 million+)
145) Richard A. Knaak (1 million+)
146) Katherine Kerr (1 million+)
147) Dave Duncan (1 million+)
148 ) A.C. Crispin (1 million+)
149) Hugh Howey (1 million+)
150 ) Joe Haldeman (1 million+)
151) Glen Cook (1 million+)
152) David Brin (1 million+)
153) Henry N. Beard (1 million+)
154) Douglas C. Kenney (1 million+)
155) Alexey Pehov (1 million+)
156) Chris Wooding (750,000+)
157) Erin Morgenstern (650,000+)
158 ) Janny Wurts (500,000+)
159) Kevin Hearne (500,000+)
160 ) Alison Croggon (500,000+)
161) Michael Gerber (500,000+)
162) Gail Carriger (400,000+)
163) Lynn Flewelling (350,000)
164) Peter V. Brett (310,000+)
165) Kate Elliott (300,000+)
166) Ben Aaronovitch (300,000+)
167) Ernest Cline (300,000)
168 ) J.V. Jones (250,000+)
169) Mark Lawrence (250,000+)
170 ) Michael J. Sullivan (250,000+)
171) Karen Miller (250,000+)
172) Sharon Lee (250,000+)
173) Steve Miller (250,000+)
174) James Barclay (200,000+)
175) Paolo Bacigalupi (200,000+)
176) Jaye Wells (200,000+)
177) Gail Z. Martin (180,000+)
178 ) David Dalglish (175,000+)
179) Daniel H. Wilson (160,000+)
180 ) Adam Roberts (150,000+)
181) Glen Duncan (150,000+)
182) Scott Lynch (145,000+)
183) R. Scott Bakker (125,000+)
184) Glenda Larke (120,000+)
185) James Lovegrove (100,000+)
186) Russell Kirkpatrick (70,000+)