In the 1985 film "Rambo: First Blood Part II," the female Vietnamese agent who helps Rambo is Co Bao. She serves as his assigned local contact during a mission to investigate reports of American prisoners of war still held in Vietnam.
Co Bao arranges for Rambo to travel upriver with local river pirates so he can reach the suspected prison camp. Although Rambo is ordered only to photograph the camp and avoid direct engagement, he confirms that prisoners are present and rescues Banks, one of the captured Americans.
After the pirates betray them, Co Bao continues helping Rambo. She later infiltrates the camp in disguise, helps him escape captivity, treats his wounds, and asks him to take her to the United States. Their attempted withdrawal is interrupted by Vietnamese soldiers, and Lieutenant Tay shoots Co Bao. Rambo later avenges her by killing Tay with an explosive-tipped arrow.
The character is also identified in some references by the fuller name Co Phuong Bao, but “Co Bao” is the name used in the film’s plot and is a fair canonical answer to the question. She was played by Julia Nickson, whose performance made the character a memorable ally in the series.