Ho Yinsen (portrayed by Shaun Toub) is a character in the Iron Man film and plays a pivotal role in the development of the character of Iron Man. In both the film and in Marvel Comics, he helped Tony Stark to build the first Iron Man suit while both of them were held captive by terrorists and forced to build a Stark Industries missile system. It was Yinsen who originally saved Stark's life after his heart was critically wounded, building the electromagnet that prevented Tony's heart from being pierced by shrapnel.
Tony and Yinsen bonded whilst in captivity, befriending one another as they worked on building the Iron Man prototype. Yinsen spoke of his village and his family, stating he would see them when he and Stark escaped. Unfortunately, as the two were completing the suit, the terrorists went to check on them. After one terrorist was killed by triggering a booby trap on the cell door, Yinsen decided to buy Stark time to finish powering up the suit. He grabbed the dead terrorist's rifle and started firing wildly inside the cave to throw the terrorists into disarray. Sadly, the terrorists assembled quickly and then gunned Yinsen down.
As Stark fought his way through the cave with the Iron Man armour, he caught up with Yinsen who was bleeding to death. Yinsen stated that his family was dead and that he was going to meet them. He urged Stark to hurry and escape and to let his second chance have meaning. He then died from his wounds.
Yinsen's actions and words would have a profound impact on Tony, who upon returning to the United States closed down the weapons development arm of Stark Industries and devoted himself to fighting terrorism as Iron Man.