Joe Manganiello is the man with the dragon tattoo … as in, he got a gigantic dragon tattoo stretching from his knee to his belly button to cover his scars from his mysterious health battle.

The actor showed off the massive ink on InstagramMonday while promoting his memoir, “Bloodlines,” writing … “In chapter four, I related my struggle with the illness to my body sending out knights to fight a (western) dragon that didn’t exist.”

Joe says the soldiers in the metaphor would “punch holes throughout my body” when they “couldn’t find an enemy” … describing the nearly-fatal ailment he battled for years.

He says the three-foot dragon covering his surgery scars was “my effort to take back what little agency I felt that I had, and to signal to my body to stop attacking the dragon… because the (eastern) dragon was me…”

Joe had previously shared some gnarly photos of his battle scars after surgery … where you can see the literal hole in his stomach after doctors removed his ostomy bag and reconnected his digestive tract.

The “Magic Mike” star has said that he’s now symptom-free and off his meds after spending 7 years fighting his mystery illness.