uncommon n medium humanoid 

Perception +7; darkvision

Languages Common, two other languages

Skills Deception +11, Diplomacy +11, Society +8, Stealth +8

Str +3 Dex +3 Con +0 Int +1 Wis +2 Cha +4

AC  18; Fort +5, Ref +10, Will +11

HP 50

End the Charade [R] (attack) Trigger The doppelganger is transformed with Change Shape and another creature moves adjacent to it or takes a hostile action against it. Effect The doppelganger reverts to its natural form and can make a Strike against the triggering creature. If the creature was unaware the doppelganger was in disguise, that creature is flat-footed against this attack.

Speed 25 feet

Melee [>] claw +10 (agile), Damage 2d6+5 slashing

Arcane Innate Spells DC 21; 3rd mind reading (at will)

Change Shape [>] (arcane, concentrate, polymorph, transmutation) The doppelganger takes on the specific appearance of any Small or Medium humanoid who it has seen and whose appearance it remembers. This doesn't change the doppelganger's Speed or its attack and damage bonuses with its Strikes but might change the damage type its Strikes deal (typically to bludgeoning).

Bestiary, page 103.