Worldwide, who are the 10 most read authors measured by books sold regardless 
of genre (fiction, nonfiction etc)?

The Internet Public Library (IPL) receives this question frequently and their 
answer is located at http://www.ipl.org/ref/QUE/FARQ/bestsellerFARQ.html

"[A] question we get asked frequently is 'Who are the world's bestselling 
authors of all-time?'. We haven't found a list, but a check of the Guinness 
World Records' entry for Best-selling Fiction Author finds Agatha Christie at 
the top, with an estimated 2 billion copies of her works sold."

They also answer the bestselling book question with:

"When we get asked these questions about bestselling books, we always have to 
remind our patrons that their question is basically unanswerable. No one really 
knows which books have sold the most copies in history, because we simply don't 
have records that cover all of history! As such, any answer that we find is 
essentially just a "best guess" that is based upon estimates made by historians 
and other experts. 

Probably the most often cited estimates come from a book titled The Top 10 of 
Everything by Russell Ash. The following lists come the The Top 10 of 
Everything, 1997 (DK Pub., 1996, pp 112-113.)"

The Top 10 Bestselling Books of All Time (according to IPL):

1. The Bible
"No one really knows how many copies of the Bible have been printed, sold, or 
distributed. The Bible Society's attempt to calculate the number printed 
between 1816 and 1975 produced the figure of 2,458,000,000. A more recent 
survey, for the years up to 1992, put it closer to 6,000,000,000 in more than 
2,000 languages and dialects. Whatever the precise figure, the Bible is by far 
the bestselling book of all time." 

2. Quotations from Chairman Mao Tse-tung (Little Red Book)
"Chairman Mao's Little Red Book could scarcely fail to become a bestseller: 
between the years 1966 and 1971 it was compulsory for every Chinese adult to 
own a copy." 

3. American Spelling Book by Noah Webster
"First published in 1783, this reference book by the American man of letters 
Noah Webster (1758-1843) remained a bestseller in the U.S. throughout the 19th 
century." 

4. The Guinness Book of Records
"First published in 1955, The Guinness Book of Records stands out as the 
greatest contemporary publishing achievement. There have now been 37 editions 
in the UK alone (it was not published annually until 1964), as well as numerous 
foreign-language editions." 

5. The McGuffey Readers by William Holmes McGuffey
"Published in numerous editions from 1853, some authorities have put the total 
sales of these educational textbooks, originally compiled by American 
anthologist William Holmes McGuffey (1800-73), as high as 122,000,000. It has 
also been claimed that 60,000,000 copies of the 1879 edition were printed, but -
 since this is some 10,000,000 more than the entire population of the U.S. at 
that time - the publishers must have been extremely optimistic about its 
success." 

6. A Message to Garcia by Elbert Hubbard
"Now forgotten, Hubbard's polemic on the subject of labor relations was 
published in 1899 and within a few years had achieved these phenomenal sales, 
largely because many American employers purchased bulk supplies to distribute 
to their employees." 

7. The Common Sense Book of Baby and Child Care by Dr. Benjamin Spock
"Dr. Spock's 1946 manual became the bible of infant care for subsequent 
generations of parents. Most of the sales have been of the paperback edition of 
the book." 

8. World Almanac
"Having been published annually since 1868 (with a break from 1876 to 1886), 
this wide-ranging reference book has remained a constant bestseller ever 
since." 

9. The Valley of the Dolls by Jacqueline Susann
"This tale of sex, violence, and drugs by Jacqueline Susann (1921-74), first 
published in 1966, is perhaps surprisingly the world's bestselling novel. 
Margaret Mitchell's Gone With the Wind, which has achieved sales approaching 
28,000,000, is its closest rival." 

10. In His Steps: "What Would Jesus Do?" by Rev. Charles Monroe Sheldon
"Although virtually unknown today, American clergyman Charles Sheldon (1857-
1946) achieved fame and fortune with this 1896 instructive religious treatise 
on moral dilemnas." 


Other popular lists regarding bestsellers are:

Bestselling Children's Books of All-Time
http://infoplease.lycos.com/ipea/A0106194.html

Modern Library's 100 Best Novels
http://www.bookspot.com/listmodern100.htm

Publisher's Weekly Bestsellers
http://www.publishersweekly.com/bestsellersindex.asp

The New York Times Bestsellers
http://www.nytimes.com/pages/books/bestseller/index.html

USA Today's Weekly Best Seller List
http://www.usatoday.com/life/enter/books/leb1.htm

All-Time UK Bestsellers (BBC News/Whitaker BookTrack)
http://news.bbc.co.uk/hi/english/entertainment/arts/newsid_1528000/1528551.stm

Darn, guess I cant find the top 10 authors, but thank you for all the other 
information

some additional information from the same article...

World's Bestselling Fiction
Ash notes in his preface to this list that "Although only Jacqueline Susann's 
The Valley of the Dolls appears in the all-time list, and publishers' precise 
sales data remain tantalizingly elusive (it has been said that the most widely 
published fiction is publishers' own sales figures), there are many other 
contenders for this list. It seems certain that all the titles in this list 
have sold in excess of 10,000,000 copies in the hardback and paperback 
worldwide." 

Bach, Richard. Jonathan Livingstone Seagull 
Blatty, William. The Exorcist 
Benchley, Peter. Jaws 
Caldwell, Erskine. God's Little Acre 
Heller, Joseph. Catch-22 
Lee, Harper. To Kill a Mockingbird 
McCullough, Colleen. The Thorn Birds 
Metalious, Grace. Peyton Place 
Mitchell, Margaret. Gone With the Wind 
Orwell, George. 1984, Animal Farm 
Puzo, Mario. The Godfather 
Robbins, Harold. The Carepetbaggers 
Salinger, J.D. Catcher in the Rye 

Bestselling Children's Authors in the World
Ash notes that "based on total sales of their entire output", the following 
authors "have produced titles that have been bestsellers - especially those in 
numerous translations - over a long period." 


René Goscinny and Albert Uderzo
"René Goscinny (1926-77) and Albert Uderzo (b. 1927) created the comic strip 
character Astérix the Gaul in 1959. They produced 30 books with total sales of 
some 250,000,000 copies." 
Hergé
"Georges Rémi (1907-83), the Belgian author-illustrator who wrote under the pen 
name Hergé, created the comic strip character Tintin in 1929. Tintin appeared 
in book form from 1948 onward. He achieved worldwide popularity, and the books 
have been translated into about 45 languages and dialects. Total sales are 
believed to be at least 160,000,000." 
Enid Blyton
"With sales of her Noddy books exceeding 60,000,000 copies, and with more than 
700 children's books to her name (UNESCO calculated that there were 974 
translations of her works in the 1960s alone), total sales of her works are 
believed to be over 100,000,000, making her the best-selling English-language 
author of the 20th century." 
Dr. Seuss
"His books in the U.S. Top 10 alone total about 30,000,000 copies: to this must 
be added those titles that have sold fewer than 5,000,000 in the U.S. and all 
foreign editions of his books, suggesting total sales of more than 
100,000,000." 
Beatrix Potter
"The Tale of Peter Rabbit (1902) was one of a series of books, the cumulative 
total sales of which probably exceed 50,000,000." 
Lewis Carroll
"Total world sales of all editions of Carroll's two classic children's books, 
Alice's Adventures in Wonderland and Alice Through the Looking Glass, are 
incalculable. However, just these two books probably place Lewis Carroll among 
the 20 bestselling children's authors of all time." 

B. Other Lists 
Russell Ash isn't the only one compiling such lists, though. Publishers Weekly, 
the leading magazine in the publishing industry, has some lists of their own. 
Here are links to their lists: 

All-Time Bestselling Children's Books -- this list cover sales through the end 
of 2000, and was compiled from sales data given by the publishers themselves. 
The Poky Little Puppy tops the Hardcovers list, with sales of 14,898,341. 
Charlotte's Web (9,899,696 in sales) tops the Paperbacks list. 

Top of the Reel -- a list of the all-time bestselling audiobooks, from 6/25/00. 
Topping the list, with 1.5 million sold, is The Seven Habits of Highly 
Effective People. 
Publisher's Weekly also compiles lists every year of the bestselling hardcover 
fiction, hardcover nonfiction, trade paperback, and mass market paperback books 
of the past year. You can check for these on their web site or through the 
Information Please Almanac's section on Books, if you like. 

Another question we get asked frequently is "Who are the world's bestselling 
authors of all-time?". We haven't found a list, but a check of the Guinness 
World Records' entry for Best-selling Fiction Author finds Agatha Christie at 
the top, with an estimated 2 billion copies of her works sold. 

Guinness' web site also offers a few more records, such as: 

Best-selling children's book series -- R.L. Stine's Goosebumps series, whose 80 
titles have sold 220 million copies worldwide. 
Best selling diary -- The Diary of Anne Frank, which has sold more than 25 
million copies. 
Highest one year sales for a book series -- The first three books in JK 
Rowling's Harry Potter series sold 23 million books in 1999. 
Finally, for those who are curious about the various best-seller lists that are 
compiled by places like The New York Times, USA Today, and the San Francisco 
Chronicle, look no further than this informative Slate article from 1998, The 
Book Industry's Best-Seller Lists - What are they, and why do they matter so 
much?, which discusses what "best-seller" really means, and how the various 
lists differ from one another.

The question was about witch AUTHOR who have sold most books.
Not wich BOOKS as you guys are talking about.

ASTRID LINDGREN, the swedish child book writer.
Is definitively one of the most read authors in the whole world.
Her books (more than 15 different characters, and at least 40 books)
has been translated to more than 50 different languages!

You probably recognise her books about PIPPI LONGSTOCKINGS
(Swedish name: Pippi Lĺngstrump), and MIO MY MIO (Swe: Mio min mio),
and ofcourse the books about EMIL (Swe: Emil i Lönneberga).
See this site for more examples, http://www.astridlindgren.se/

She have sold at least 75 million copies worldwide.
And that may be an understatement.
I am sorry that I have no precise numbers to present you.

Well, just an addition, at least in Spain, Unamuno's "El érbol de la
ciencia" has been the top selling novel since it was first published.