Kevin Costner has quite possibly made one of the worst decisions of his long career by dropping out of writer/director Quentin Tarantino's "Django Unchained", in which he was slated to star in a supporting role as perverse slave trainer Ace Woody.

When it was announced that the Costner had joined the project back in July, it seemed like a perfect bit of casting that might potentially revive the actor's career, which over the last decade or so has been checkered at best. Unfortunately, a combination of scheduling conflicts and personal reasons compelled him to exit, according to scoop-getter Deadline.

"Django Unchained" stars Jamie Foxx as the title character, a former slave who sets out to rescue his wife from cruel plantation owner Calvin Candie, played by Leonardo DiCaprio (playing against type, in typical Tarantino fashion). The film also stars Christoph Waltz as a German bounty hunter and Samuel L. Jackson as a house slave who functions as DiCaprio's right-hand man.

The role of the wife hasn't officially been cast, though I would love if reported candidate Kerry Washington ends up bagging the gig (at least to balance out the casting of Foxx, who - let's face it - has become progressively more obnoxious in the years since his Oscar win for "Ray" in 2004).

Costner recently signed on to play Superman's adoptive father Jonathan Kent in Zack Snyder's "Man of Steel". His last film was "The Company Men" opposite Ben Affleck, Tommy Lee Jones and Chris Cooper.

"Django Unchained" is set to begin production this November, with a scheduled release on Christmas Day 2012.