Ask anyone who has watched a lot of movies and they’ll tell you. It’s damn difficult to make a sequel to a popular film that’s actually as good as the original. There are exceptions, of course, but they’re typically few and far between. James Cameron – who celebrates his birthday today – was responsible for two of the greatest examples of a sequel that can actually hold a candle to the original film. Terminator 2: Judgement Day and Aliens.

When you talk to horror fans about their favorite action movie, undoubtedly Aliens comes up. It conquered both the action and horror genres, and did so in such a phenomenal and outstanding way that each subsequent entry into the Alien franchise is inevitably held up for comparison.

Aliens extrapolated the journey of Ellen Ripley, who was already an incredible character and a heavy-hitter in the world of female protagonists. Thanks to James Cameron, her character was launched into total badass territory. Our vision of Ripley was forever changed with the utterance of a now iconic line – “Get away from her you bitch!” – as she stepped up and threw down.

Part of the magic of Aliens is that it doesn’t try to be like the original film. It builds on the world created by Ridley Scott and adds a whole new cast of characters that we – as an audience – immediately root for. They’re brash, they’re gruff, but dammit, they’re phenomenal.

The Weyland-Yutani Corporation is given a smarmy new presence with the addition of Burke (Paul Reiser), a company man through and through. He knowingly puts the rest of the team in terrible danger in the hopes of securing an implanted alien to bring back from their doomed rescue mission. He’s, frankly, such an asshole, but he’s so useless (in a practical sense) that he doesn’t pose a larger threat than the Xenomorphs themselves.

And of course, there’s the Xenomorphs. A perfect movie monster to begin with, in Aliens they’ve multiplied the threat. A whole bunch of times. And added in a Queen. Because what better way to increase the terror of the first film? But, true to the awesomeness of the 80s, this new thrilling entry had to be a full-throttle, guns-blazing, explosive action extravaganza.

While many prefer the tense, unexpected thrills of Alien, the sequel had to branch out and go bigger. Once you’ve seen the true terror of the chestburster scene once, you can’t recreate it and expect the same reaction. Aliens needed to draw a bigger and broader audience, and it had to bring something new to the table.

So, Cameron did. He amped up the action, the raised the stakes, and he won over fans of horror and action alike. Aliens was one of the first films I remember seeing as a child, and it had a huge effect on me.

Speaking of films that had a huge influence on me, that brings me to Cameron’s next sequel.

Terminator 2: Judgement Day took the heroine of The Terminator and gave her a killer upgrade. We hadn’t seen Sarah Connor for quite some time, and she while she wasn’t exactly a shrinking violet in the first film, she trembled in terror beside the unstoppable force of terror that was pumped-up Arnold Schwarzenegger.

In Terminator 2, however, the T-1000 couldn’t even make this weary warrior blush. Like Ripley, Sarah Connor grew from her traumatic experience and became what she was always meant to be – a hardened and unflappable killer queen.

Of course, one of the other fantastic aspects of T2 was the humor and humanity that it brought to the one-fearsome literal killing machine. Again, Cameron knew that he couldn’t simply recreate the first film and expect the same results. He had to give us something new.

And new it was, though that didn’t mean he was pulling any punches. The T-1000 – like the Xenomorphs of Aliens – needed to bring something bigger, stronger, and scarier to the table. Cameron understood that you can’t just hit the same notes as the original film; there needs to be growth.

For this, we really need to give the man more credit. Building a franchise is hard, and arguably we wouldn’t have two of the most recognizable franchises in modern pop culture if it wasn’t for his efforts.

No matter how you feel about the films following, you can easily say that T2 and Aliens weren’t just successful, they were genuinely great movies.