If you like
Roger Zelazny, you'll love Steven Brust! Brust is best known for his
Vlad Taltos series (
Jhereg,
Yendi,
Teckla,
Taltos,
Phoenix,
Athyra,
Orca,
Dragon,
Issola), about an
assassin in
Dragaera (Dragaera is to Brust as
Amber is to Zelazny or
Xanth is to
Piers Anthony, if you'll pardon the rather general
analogy). All of the Vlad novels are absolutely excellent. In addition, Brust has written (and is writing) several other novels that take place in Dragaera (which, I must say, is one of the most detailed
fantasy worlds any
author has ever created).
The Phoenix Guards and its sequel,
Five Hundred Years After, are excellent adventure yarns that take place some 1,000 years and 500 years (respectively) prior to Vlad's
timeline.
Brust has also written quite a few "standalone" novels. Prime among them are To Reign in Hell, an intriguing "what if"-style account of the war in Heaven referred to by the opening paragraphs of the Bible. Roger Zelazny particularly liked To Reign in Hell, coincidentally. Also very much worth reading are Agyar; The Sun, the Moon and the Stars; and (if you want something a little more pulpy and silly) Cowboy Feng's Space Bar and Grille.
In my opinion (and that of many other people) Steven Brust is one of the best Sci-Fi/Fantasy authors alive.