He’s lived his life in the shadows for 30 years (1987-2016) in the service of his country, and he likes to be unremarkable yet very efficient. Hellbent on eliminating the presence of the Transformers on Earth, he mercilessly stalks human mechanic Cade Yeager and his daughter Tessa, due to their alliance with the Autobots. He works alongside a Transformer bounty hunter for the duration of the movie. He is given the Seed, a Cybertronian bomb built by the Creators that is able to turn the surrounding landscape into Transformium, an unstable metal the transformers are made of, by Lockdown after he captures Optimus Prime. Attinger attempts to give the Seed to Joyce in return for his payment, but Joyce leaves the scene, knowing that Galvatron wants that Seed to rebuild his army. At the end of the film, Galvatron seemingly retreats as his army is destroyed and Lockdown returns to fight Optimus. Attinger notifies Lockdown of the situation, the location of the Autobots and the Seed they have stolen. He coners Cade with a gun while Optimus fights Lockdown and he rants about how it takes patience to make a man and to work in the shadows to protect all humans. He claims that there are no good aliens or bad aliens, it's just the humans and them. He says to Yeager, "You chose them" and is about to shoot Yeager, but is quickly shot in the chest by Optimus, killing him on impact and avenging the deaths of the Autobots he had killed.
Attinger was a no non-sense man with strict objectives and zero compassion for his enemies, even if they were innocent people. Though he hated Transformers, he was willing to join forces with them if it meant to farther his goal, such was the case with Lockdown (who shares this believe even though he's a transformer himself). Though all this may come from his years of working in the shadows, causing him to become paranoid and fearful, specially after the battle of Chicago. Strangely, despite being ruthless and paranoid, he was known for his calm and patient demeanor unlike Dylan Gould was. Rarely did Attinger raise his voice or over react to a situation, instead planning it out as it unfolded. Attinger also revealed himself as the Master Manipulator near the climax, as he revealed to Joshua that all this time, he had little to no care towards both Joshua and KSI despite considering them as his "golden parachute of his goal". Despite claiming himself to be saving the world from the threat of the Transformers, a majority of the destruction and death in the film is caused by him and his organization of Cemetery Wind. Whether he sees it or not, he's a hypocrite considering that he couldn't allow any rescue services to recover the injured when innocent people were caught in the crossfire of Galvatron's attack on the Autobots, and even allows Lockdown to level Hong Kong to find Optimus and hide his co-operation.
- Despite his hatred for Transformers, he secretly made a deal with Lockdown (who seemed to share a mutual contempt towards his own kind) to get a MacGuffin known as the "Seed," which can turn organic life into a metal called Transformium to make new Transformers for the private sector. Even though the deal was complete, he informed Lockdown of the Seed being taken, upon his confrontation with Joshua Joyce.
- Also ironic is that Lockdown hates humans despite working for/with Attinger.
- Harold Attinger can also be considered as Lockdown's human counterpart.
- His deed when he having Joshua Joyce recreated Megatron into Galvatron somewhat similar with how Unicron evolved/recreated Megatron into Galvatron. Both also tries to have them works for them, and considering the movie creators previously intended to use Cyclonus as another major antagonistic Cybertronian before they choose Lockdown instead, Harold Attinger was meant to replace Unicron as well. Ironically, damage that Harold received when Galvatron turned on him was more severe than Unicron had, something that Joshua had been warned about by Cade before he betrayed Attinger previously.
- Lockdown is often thought to be the film's primary antagonist; however, Attinger is the main antagonist because he is the cause of the film's plot and has deeper motives. In his role as director of Cemetery Wind, he hired Lockdown to hunt and eradicate all transformers from earth (Which the plot is focused on). He is the second human antagonist in the series after Dylan Gould and the first to be the main villain of a movie.
- Dylan Gould, Lockdown, The Fallen & Attinger are the only Transformers movie villains to be considered Complete Monsters, as they are universally hated by many due to their horrid actions. In fact, it's probably because Dylan and Attinger are humans that they're considered so. Unlike Dylan Gould, however, Attinger is less cowardly and he committed his villainous deeds in both a far more serious and competent manner than Dylan ever did.
- Harold Attinger will become Brian, Thomas, Twilight, Roary, and Theodore's enemy in Brian Griffin's Adventures of Transformers: Age of Extinction.
- Harold will become Jimmy Neutron's enemy in Jimmy Neutron's Adventures of Transformers: Age of Extinction.
- Harold will become Ash Ketchum's enemy in Ash's Adventures of Transformers: Age of Extinction.
- Harold will become Tino's enemy in Weekenders Adventures of Transformers: Age of Extinction.
- Harold will return in The Lost Train-Bot Empire, and he, Savoy and Lockdown will try to kill our heroes.