Paul C. Doherty (also P.C. Doherty): a MOST prolific author of historical novels spanning from Ancient Egypt to the reigns of Edward I & II. He has written about Alexander's court and about Constantine I's court as well.

John Maddox Roberts: his SPQR novels set during the collpase of the Roman Republic are historically accurate and delightful in their dry humor. His hero is a junior member of one of the great and most conservative Senatorial families of the time, the Caecillii Metelli.

Steven Saylor covers the same period, but from a distinctly Plebian point of view with is Roma sub rosa series.

Lindsey Davis writes about a detective/agent of the Emperor Vespasian in the early 70s CE, Marcus Didius Falco. Falco is Mike Hammer moved back to ancient Rome except that the author uses lot of British slang her writing.

I should also note that Bernard Cornwell is now four books into a series about Alfred the (not so) Great versus the Danes in the late 9th Century, except that it is more or less from the Danes' point of view. The first book is The Last Kingdom My only problem with Cornwell is that he is as mightily anti-Christian in this series as he was in the Arthurian trilogy. Other than that, he writes one Hell of a page-turner.