The biggest one was probably 2 years back, the dispute with WP Engine, a hosting provider for WordPress. He used WordPress infrastructure to force all instances hosted there to break, then removed the extensions they built from the plugin store, and then replaced them under the exact same name and identifier with his own.
He then went on this site, and placed incriminating comments under posts discussing that, without discussing it with his lawyers. These comments were then of course used in subsequent lawsuits, which so far he's been losing.
He then also told his employees that if they didn't agree with his actions, they could leave with a severance package, which then had 10% of his employees quit.