The Alien franchise began largely as a tale of "truckers in space," focusing on the crew of a commercial towing vehicle that comes into with a horrifying alien life form. From the beginning, it became clear that certain characters excelled when it came to brain power, but it manifested itself in different ways.
Some intelligent characters were street smart, while others were either gifted or studied hard to become proficient in their particular career choice. Regardless, these characters stand head and shoulders above the rest as some of the brightest and sharpest characters in the entire Alien saga.
Dallas
Dallas was the gruff and pragmatic captain of the ill-fated Nostromo, and what he lacked in technical knowledge, he more than made up for with street smarts. When the original xenomorph got loose on the Nostromo, it was Dallas who formulated the first set of plans designed to try and trap it.
Unfortunately, Dallas underestimated the creature's cunning when he attempted to flush it out of the ship's ventilation ducts in one of the scariest scenes in the entire Aliens saga. Nevertheless, his death was not in vain, even if his loss as a noble and intelligent leader was felt in the aftermath.
Elizabeth Shaw
Elizabeth Shaw was one smart woman, possessing degrees in archaeology, paleontology and ancient myths. With her partner and lover Charlie Holloway at her side, Shaw was one part of a force that ended up pushing mankind into the far reaches of space, to uncover its own origins.
However, she got more than she bargained for when she went up against the fearsome Engineers and their horrifying bio-weapons technology. Eventually, she was killed by the android David, who went on to conduct a series of experiments that led to the creation of the praetomorph, a precursor to the deadly xenomorph.
Newt
Despite being just a little girl, Newt possessed an intelligence factor that seemed to rival those of the adults living in the Hadley's Hope colony on LV-426. When the initial infestation broke out, Newt managed to hide inside the facility's ventilation ducts, avoiding detection.
She managed to do this for weeks on end, until the Colonial Marine rescue team arrived to survey the damage. Ellen Ripley was so impressed by Newt's intelligence and resilience that she referenced her as a model for survival when the operation went sour. The two forged a mother/daughter relationship that helped Aliens stand the test of time as a film.
Dwayne Hicks
He might have been just a Corporal, but Dwayne Hicks thought much differently than the rest of his Colonial Marine squad. He was far more mature and practical, and eschewed much of the hot-headedness that plagued his team.
As such, Hicks was a natural choice for leader when the rescue op went bad. Along with Ripley, he helped devise a series of logical and practical plans to make it off the planet in one piece. Hicks was far from a typical grunt, instead possessing all the qualities that would have made him a top-ranking officer, had things gone differently.
Dillon
On a planet populated by reckless and barely-controlled felons and convicts, Dillon stood apart. That took an enormous amount of intelligence, particularly when Ellen Ripley showed up on Fury 161. Overnight, many of these hardened and wicked criminals suddenly began succumbing to temptation at the very sight of her.
Dillon managed not only to keep them in line and maintain order, but he was also instrumental in dealing with the rogue xenomorph that was terrorizing the colony. Dillon was good at planning, and he was able to adapt when circumstances changed. He is one of the most understated intellectuals in the entire franchise.
Bishop
Bishop was a successor model android who possessed even more lifelike programming and capabilities, making him nearly indistinguishable from a regular human. His ability to fit in seamlessly inside a group dynamic was one net positive, but it was his intellect that really mattered.
He had a keen scientific mind, and a curiosity to match it. Yet, he did not possess the same ruthlessness and ambition as previous android models, making him something of an anomaly. He was considered one of the smartest characters in the Alien franchise.
Ellen Ripley
Ripley was, for all intents and purposes, a trucker in space, but she was also smart as they come. Her Weyland-Yutani service profile revealed that she had incredible potential to ascend to the highest ranks within the company, which is one of the reasons they tolerated her rebellious behavior.
Even though she wasn't a master of any particular trade, Ripley made plenty of smart decisions within the Alien franchise. She was able to formulate plans with a snap of the fingers, and change them dynamically at a moment's notice. She was also a master strategist, particularly when it came to staving off xenomorph attacks.
Gediman
Gediman represented a leap forward in medical technology, particularly where genetic cloning was concerned. He was one of the foremost authorities on the subject, and his intelligence led to the creation of the Ripley clone, which they used to procure a xenomorph Queen.
Even after the operation was over, Gediman continued his research, turning Ripley into his personal pet project. He was able to quickly ascertain that Ripley's DNA had crossed with that of a xenomorph, creating a very deadly hybrid.
David
David is perhaps the most insidious android ever constructed by the sinister and mysterious Weyland-Yutani corporation, and his machinations wrought havoc on both the crew of the Prometheus, and that of the Covenant. The latter ship had picked up a distress beacon set to lure them to his location, where he could harvest more material for his experiments.
For all his scientific wizardry and nefarious goals, David was remarkably reckless. His plans were almost nullified by Walter, an identical android to himself. His determination to create the supposed "perfect lifeform" was a testament to his own madness.
Ash
Androids are a particularly prevalent trope in Alien movies, but it was Ash who got the ball rolling He remains the smartest character in the entire Alien franchise, primarily due to his ability to remain patient and low-key. He was practically immune to impatience, yet he was also quick to pounce on opportunities that he believed would advance his mission.
He also possessed an incredibly scientific mind, which was enhanced by his status as android. He could manipulate others, deflect attention away from himself, and keep people in the dark, all while orchestrating events in the background. He nearly succeeded in his goal to bring a xenomorph back to Earth, but was stopped by Ellen Ripley's sharp instincts and suspicions.
