Wow. There are an enormous number of these, and not all of them are still in print. I'll present the list alphbetically by author, and add to it at intervals. You'll note I tend toward action-adventure stuff, but the occasional romance pops up from time to time. Where the author has a series involving the same characters/situations, I've subdivided. Remember I get a kickback for each book you buy through the links presented. Despite being a voracious reader, I haven't managed to read every single one of all the books here, and I haven't had time to write capsule reviews of all of the ones I have read, so I'll leave some entries blank until I can fill them in. More authors will be added as I get time and energy.
Bernard Cornwell: Most readers of historical fiction are familiar with Cornwell, for his "Sharpe" books if nothing else. All of his books are meticulously researched, but he is not afraid to tinker with things in the interests of a better story. Cornwell's style is rapid, fast to read, and entertaining. First, a few "one off" books that don't fit into a particular series (but do not include Cornwell's thrillers -- see his website for those):
Stonehenge: I'm not in complete agreement with Cornwell's speculations from a historical point of view, but I'm not an expert by any means. In any case, this is a good story with many interesting characters, a little treachery, love, action, and a "can't put it down" plotline.
Redcoat: This one reads like it was the starting point for a series set in the American Revolution, but nothing more has come of it. Frankly, this one is not up to Cornwell's usual high standard -- it's good, but not great.
Gallows Thief: This one is set shortly after the end of the Napoleonic Wars, and deals with some of the social problems of the time and place. It is excellent, and (as with Redcoat, is set up so it could serve as the start of a series.
Then, The Sharpe books (these are in historical order, rather than publication):
The Starbuck Chronicles, following the adventures of a Yankee in Confederate service (it gets a little complex, but it's all explained in the first book, Rebel.):
The Bloody Ground
The Arthurian chronicles deal with the legends of King Arthur.
The Winter King
The Enemy of God
The Grail Quest is set in the 14th century, and deals with a quest for the holy grail by an English soldier of fortune and his companions.
The Archer's Tale
Rosemary Sutcliff: I discovered Ms. Sutcliff's works in elementary school, when I ran across The Eagle of the Ninth on the shelves of the school library. Most of her books are classified as "young adult," but they are good reads even for adult.
The Eagle of the Ninth This deals with the efforts of a young centurion to recover the lost eagle of the Ninth Legion, in the early 2nd Century AD. Current historical thinking is that the Ninth Legion (Legio IX Hispana) was destroyed elsewhere than in Britain (invalidating the key element of the plot), but the book is still worth reading despite this..
The Silver Branch
The Lantern Bearers