TMZ has learned "Jackass" star Bam Margera has been hospitalized after being attacked by a bat-wielding woman.
Cops tell us ... it happened at 2 AM this morning, outside Bam's bar in West Chester, PA. There was some sort of fight, that ended when the woman allegedly hit Bam in the back of the head with a baseball bat.
The woman was arrested and charged with assault.
Bam was taken to the Chester County Hospital. His condition is unknown.
UPDATE: According to court documents, 59-year-old Elizabeth Ray faces the following five charges: Two counts of simple assault, two counts of recklessly endangering another person and one felony count of aggravated assault.