Tired of Tudors and Borgias? If you enjoy historical fiction set in sixteenth century France, here are some novels to seek out:
Classics

Queen Margot (1845) by Alexandre Dumas (various translations). The 1572 St. Bartholomew's massacre serves as the backdrop for the political machinations of Catherine de Medici.
Heinrich Mann (translated from the German)
Young Henry of Navarre (1935). Life of Henri of Navarre from his childhood in the Pyrenees to claiming the throne of France.
Henry, King of France (1938). Sequel describing the two decades of chaos and war leading up to the King's assassination.
Jean Plaidy

Royal Road to Fotheringay (1955). Young Mary Queen of Scots at the French court.
Evergreen Gallant (1963). King Henri IV.
Dorothy Dunnett
Queen's Play (1964). The second volume of the Lymond Chronicles; Lymond travels to France to protect young Mary Queen of Scots.
Checkmate (1975). The last volume of the Lymond Chronicles; Lymond is back in France, haunted by his past as he leads an army against England.
Robert Merle

Various authors
The Wife of Martin Guerre (1941) by Janet Lewis. The story of Bertrande de Rols, whose husband Martin deserts her, then suddenly reappears after eight years. But is it really Martin who returns, or an impostor trying to usurp his place?
The King's Cavalier (1950) by Samuel Shellabarger. A young Frenchman and a young Englishwoman caught up in the wild plots and counterplots surrounding the Bourbon conspiracy against François I.
Blade of Honor (1955) by John Pugh. Cloak and dagger tale about the son of Catherine de' Medici's chief Italian advisor and the horrors of St. Bartholomew's Eve.
The Virgin Blue (1997) by Tracy Chevalier. A dual timeline story of an American midwife and her Huguenot midwife ancestor.

Courtesan (2006) by Diane Haeger. Romance of King Henri II and Diane de Poitiers.
Mademoiselle Boleyn (2007) by Robin Maxwell. Anne Boleyn's formation at the court of François I.

The Devil's Queen (2010) by Jeanne Kalogridis. Catherine de' Medici barters her soul to produce heirs.
The Confessions of Catherine de Medici (2011) by Christopher Gortner. Catherine de' Medici narrates the story of her reign. My review here.
To Serve a King (2011) by Donna Russo Morin. A female spy and assassin infiltrates François I's court.
Médicis Daughter (2015) by Sophie Perinot. Coming of age story of Marguerite, daughter of Catherine de' Medici during violent Wars of Religion. My review here.
And if you read French...

Enjoy! I'm about to plunge into The Brethren myself. And if I've missed any novels set in Renaissance France, please add them in the comments below!