Most of the books written by Alistair MacLean are fiction, but he would do a lot of research and take a lot of time to make the settings very true-to-reality (well, for most of his books, at least). Several of his novels were turned into movies, although in my opinion almost none of the movies are as good as the original novels. In some cases the movie is almost unrecognizable from the original book, but usually the movie version just leaves out some important details. Most of the movies are pretty good in their own right, it's just that they seem a step down from whatever book they were based on.
In any case, by being movies they are probably more well-known than the rest of his books which were not made into movies. So, here is a list of some of his books which were turned into notable movies, and which are therefore more likely to be titles that you would have heard of:
That last movie is actually pretty obscure, but of all the books he has written, "Fear is the Key" is my favorite. The movie version of that novel was released in the early 1970's, but I was not able to track it down until sometime around 2002. That movie version does a pretty good job of sticking to the original story, but it is still not as good as the book.
For more information on books of his which have ended up as movies, you can check out this page at the Internet Movie Database site. As I write up this web page, the IMDB lists 17 movies which were based on his writing. There also seems to be some more info on Alistair MacLean at this Where Eagles Dare home page, when that web site is available.
There is a pretty nice biography of Alistair MacLean at this kirjasto.sci.fi web page. There is also a pretty complete list of his books at this magicdragon.com web page, if you look about a quarter of the way down the page.
There is a footnote I should include about this web page (ie, the web page you are reading right now). This was first written in 1998, and I wrote it one night while in my office and with all of my Alistair MacLean books at home. So, I relied on some other web page for the spelling of Alistair's last name, and that web page had spelled it as "McLean". It turns out that all of my books at home have his last name spelled as "MacLean". You will find both spellings used in various locations on the web, and in fact there are some web sites which will list Alistair McLean and Alistair MacLean as two different authors! Since this web page often comes up as one of the top web pages when you use google to search for "Alistair McLean", I thought I should continue to include several references to that spelling.