Whoever broke into Charlie Villanueva's house, that's who ... this according to the NBA player himself.

Villanueva -- who made more than $50 million in his career -- says he came home to his Dallas pad and realized someone had been inside and stole a bunch of his stuff.

But the worst offense ... "They stole my toilet ... I'm not making this sh*t up!"

Villanueva even provided photo evidence of the jacked crapper.

"I’m still tripping, who steals a toilet? Like why a toilet."

A few hours later, Charlie added, "I’m still in shock of the things they stole ... but the one that stand out the most is a toilet...... Bro a toilet, can’t get my mind off that. A toilet..... Wow."

Must have been a nice toilet.