Librarian Note: There is more than one author in the GoodReads database with this name. See this thread for more information.Peter O'Donnell also wrote as
Madeleine Brent.
http://www.cs.umu.se/~kenth/modesty.htmlis an excellent resource on this author.
To help keep the novels and the adventure strip collections separate, here's some info about the Modesty Blaise works.
In 1963, O'Donnell began his 38-year run as writer of the Modesty Blaise adventure story strip, which appeared six days a week in English and Scottish newspapers. He retired the strip in 2001.
Each strip story took 18-20 weeks to complete. Several publishers over the years have attempted to collect these stories in large softcovers. Titan Publishing is currently in the process of bringing them all out in large-format softcover, with 2-3 stories in each books. These are called "graphic novels" in the Goodreads title.
Meanwhile, during those 38 years, O'Donnell also wrote 13 books about Modesty Blaise: 11 novels and 2 short story/novella collections. These stories are not related to the strip stories; they are not novelizations of strip stories. They are entirely new, though the characters and "lives" are the same. These have been labeled "series #0".
There is a large article on Peter O'Donnell on Wikipedia, with a complete bibliography.