Douglas Hunsiker is the teritary antagonist of the film Rise of the Planet of the Apes and also the man directly responsible for the spread of the ALZ-113 pandemic across the world.
He is portrayed by British-born Canadian actor, writer, director and voice actor David Hewlett who is best known for his role as Dr. Rodney McKay on the American-Canadian sci-fi series, Stargate SG-1, Stargate Atlantis and Stargate Universe.
A bad tempered neighbor of the Rodmans, Hunsiker often spent his time living at home in San Francisco, taking care of his two sons and daughter when he wasn't working as an airline pilot.
One day, Caesar, a chimpanzee who inherited a drug called ALZ-112 from his mother Bright Eyes, had been in conflict with Hunsiker when he was five years old.
Caeser saw Hunsiker's children riding on their bikes and left the Rodman house before entering the Hunsiker's garage, looking for a bike.
Alice, Hunsiker's daughter saw what was happening and fled, instantly alerting her father.
In response, Hunsiker grabbed a baseball and in a violent rage tried to attack the defenseless fleeing Caesar with Caesar's leg being cut in the process while Will Rodman and his father, Charles arrived to stop Hunsiker and save Caesar. Will and Charles comforted Caesar while promising that Hunsiker would not see Caesar again, with Hunsiker believing that Caesar would have attacked his children if he hadn't intervened.
Later, Charles Rodman who was suffering from dementia, went inside Douglas Hunsiker's car which was apparently unlocked and was turned on. Charles damaged Hunsiker's car by smashing it back and forth between the cars parked between it. Hunsiker had grabbed Charles out of his car and pulled out his cell phone to call the police. Charles attempted to verbally talk Hunsiker out of it while Caesar watched the situation out the window at home.
Hunsiker kept poking and threatening Charles, claiming that it was his problem and he was responsible for getting himself into trouble. Caesar, angry at how his grandfather figure is at the mercy of a neighbor he hates, dived onto Hunsiker punching him several times.
Hunsiker pulled out a trash lid and struck Caesar's face with it, giving Caesar a scar on his face, before Hunsiker tried to run back to his house. Caesar kicked Hunsiker from retreating to his house. Hunsiker would then try to run off, but Caesar was climbing the trees and dived on him again. Caesar then bit Hunsiker's right index finger off by accident while Charles ordered Caesar to stop.
With Hunsiker left to whimper from his pain, Caesar was sent to the San Bruno Primate Facility.
At the Gen-Sys Lab, a clumsy scientist named Robert Franklin had accidentally forgotten to put his mask on while scientists were releasing the ALZ-113 drug to a bonobo named Koba, which made Franklin inhale the ALZ-113. Robert Franklin had tried to get to Will Rodman, then Hunsiker met Franklin.
After Franklin sneezes on Hunsiker, he aggressively ordered Franklin to leave with Franklin dying days later.
In the ending credits, Hunsiker was going to work and had his bitten finger treated with a metal bandage. His nose was dripping blood, showing that Hunsiker was infected with the ALZ-113. Hunsiker flew his plane from Sacramento, USA to Paris, France, where he spread the ALZ-113 pandemic to the people in Paris, France, which led to Europe becoming entirely infected. The pandemic spread from Paris to the continent of Africa, before spreading to Asia. North and South America were already infected with the ALZ-113 pandemic which means that the human race is doomed to extinction while allowing the apes to become more intelligent.
Hunsiker was a crass and bad tempered man who seemed to be almost paranoid on the well-being and security of his property as well as his children, which was based on why he hated his neighbors the Rodmans (including associates of them such as Caesar and Robert Franklin themselves), for no apparent reason; he assaulted a dementia-stricken elderly man - arguably understandable given the circumstances - and threw Robert Franklin out of the street, which was fairly unreasonable considering that Robert was trying to see his employer at the time, while it's most likely Hunsiker suspected Robert was simply trespassing in the neighborhood (including Hunsiker's own home), rather then trying to warn Will as he caught Robert exhibiting suspicious behavior by desperately pounding against his neighbors' back door after nobody answered Robert who was knocking at the front door.