Susan Sarandon had an unwanted visitor with major cajones ... a guy who used a ladder to climb in from the building next door and then burglarize her.
According to police ... Sarandon's son Miles -- who lives with her -- returned home around 5:00 AM Sunday and the apartment was a complete mess. The thief made off with a laptop, jewelry and a camera.
Cops say there was no sign of forced entry and after investigating ... cops found a ladder on the roof of the building next door, which they believe he used to scale the buildings.
Here's the problem ... there are no security cameras on the roof so there's no description of the burglar.
Sarandon was not around for any of this.