Earth vs. the Spider featured a blown-up tarantula. It lived in a cave and was suggested to be the result of nuclear radiation.
There was a 2000s film with the same name about a guy who injected himself with spider DNA in an attempt to become a super-hero, only to mutate into a grotesque humanoid arachnid-thing that was eternally hungry and devoured people indiscriminately. It was basically a horrifying parody of Spider-Man.
Eight Legged Freaks, with somewhat better special effects, is an Affectionate Parody of this type of film. A small town is beset by a Spider Swarm, with critters varying in size from large dogs to a tank (the "Queen" spider at the end).
The Giant Spider Invasion made use of laughably bad puppetry. Its spiders were actually from another dimension that had been opened up by a meteorite landing in a farmer's field. A very stupid movie.
Horrors of Spider Island has surprisingly few spiders. Just the one, which is about the size of a human head, and a guy who becomes a mutant after he gets bitten by the aforementioned spider on the eponymous Island of Mystery.
Itsy Bitsy involves the summoning of a spider the size of a small dog (that gets bigger whenever it sheds its skin) into the home of a young mother and her children from a stolen vase.
One Million Years B.C. very briefly featured a blown-up tarantula lurking in a prehistoric desert. It was one of the few non-stop-motion creatures in the movie.
Tarantula! featured a blown-up tarantula, although it used a model for closeups.
Arachnia has prehistoric giant spiders awoken by a meteor as the main antagonists.
The 2000-01 movie duology (actually two unrelated films) Spiders and Spiders II: Breeding Ground of course feature giant spiders as the main foe. In the first one they were the result of a freak experiment on a space satellite due to a meteor storm, in the second they were created by a mad scientist who wanted to make a stronger human race... somehow.
Arachnicide: The main antagonists are a horde of giant, super-aggressive spiders made by genetic engineering to destroy a commando unit for a drug cartel.
Arachnid is about a giant spider infestation on a small island near Guam.
Arachnophobia: The largest spider in the aptly-named film is not very big compared to Kumonga, but still slightly bigger than any real spider. Even Australian ones. The real problem with the spiders in said film are their sheer numbers and insanely venomous bite.
Beowulf (1999): Grendel's Mother transforms into a spider hybrid to fight Beowulf.
Camel Spiders: While camel spiders are already pretty pig in real life (they typically grow to six inches in length), the Creepy Camel Spiders in this movie can become as big as a grown person's head. Even the smaller ones are the size of a show.
Crazy Spider (or, alternatively, its international title, Abyssal Spider): The titular monster is a giant spider. It starts off the size of the truck, but it soon grows out of control until it becomes kaiju-sized.
Dr. Jekyll and Mr. Hyde (1920): One Transformation Sequence in the silent film version features one; Jekyll sees a transparent giant spider crawling towards him, and once it reaches its destination, it disappears and he has turned yet again into Mr. Hyde.
Enemy: These appear in various dream sequences. Not to mention in the Gainax Ending.
The Fly (1958): At the end, a fly with a tiny human head — the other half of the movie's human/fly Mix-and-Match Critters — is menaced by a normal-sized spider. "Heeeelp meeeee!"
S minor arachnid-themed monster, Scylla, spends most of the movie hibernating in the Arizona Desert until King Ghidorah awakens it to go on a rampage. The end credits however reveals Scylla to be a Sea Monster closer in relation to crabs.
The Hobbit: The Desolation of Smaug: The monstrous spiders of Mirkwood, lesser spawn of Ungoliant, aren't quite as big as Shelob... but are still plenty huge, and have similarly horrific maws. And, when Bilbo's wearing the One Ring, he can understand their speech.
Ice Spiders, wherein Olympic athletes are terrorized by, you guessed it, Giant Spiders at a ski resort.
The Incredible Shrinking Man: The titular character encounters an ordinary-sized spider which is huge to him. The film couldn't afford a fake spider, so they just used a real one filmed up close. Sweet dreams.
Jumanji: One of the last things to come from the game are giant spiders. They didn't do much, as they got scared off by the earthquake in the very next turn, but they were still one of the more memorable and frightening parts of the film... even if they look more like wind-up toys.
Giant spiders constituted most of one of the most legendary (or, as some claim, overhyped) deleted — and now lost — scenes in film history: a section of King Kong (1933), now known as the Lost Spider Pit scene. The footage is now believed to be lost forever, but the scene was re-created as a bonus feature over 70 years later, with stills and concept art used as reference.
King Kong (2005) features giant spiders (detailed in the Natural History of Skull Island as spider-like arachnids called "Arachno-Claws") in the Bug Pit scene. Based on the above mentioned 1933 example, of course.
Kong: Skull Island: In one scene, the characters are attacked by a gigantic spider-like creature so tall that its legs blended into the bamboo forests they were walking through. It impales one of them with its leg and attempts to draw another up by its fleshy tendrils into its Belly Mouth. On the Skull Island MONARCH website, it's given the name of Mother Longlegs and isn't actually a spider, but a colossal harvestman that's also part bamboo, and all female, with mouths at the ends of its spiked legs.
King Solomon's Mines (1985): A giant spider attacks a mook and eats him in a scene.
Krull: One of the side plots involves a giant albino spider guarding/imprisoning an oracle in a rather comfortable-looking cocoon in a gigantic web. It moves to eat anyone coming to consult with her and is only prevented when she pours the sands of her life away (freezing it in place while the sands are in motion).
The Magic Serpent: A giant spider appears at the very end for the Big Battle. She is a good guy, though. She throws silk and snow (yes, snow) over the title creature to subdue him.
Michael Jackson's This Is It features a gigantic black widow spider during the "Thriller" segment. Not only is one on-screen (this would have been in 3D, no less), but one scurries on stage that opens up to reveal Jackson himself.
The Mist features giant spiders which spray acidic webs as one of the many monsters that attack the characters.
Monster Hunter (2020): The giant spiders known as Nerscylla are responsible for the deaths of much of Alpha Team, and Artemis probably spends more time fighting than any other monster. (That said, the other monsters mostly appear singly, while the Nerscylla are a swarm.)
The Muppet Christmas Carol: Old Joe, the fence who receives Scrooge's bed linen, is portrayed as a spider in a battered top hat, about the same size as a typical Muppet.
Jon Peters:
Having produced The Film of the Series for Wild Wild West, one could think that producer Jon Peters included the giant Steampunk mechanical spider as an attempt at an interesting sequence. Contrary to popular belief, however, the spider wasn't Peters' idea: that was from the original script, and Peters was initially opposed to including the spider. However, the man has an apparent fascination with giant arachnids: Kevin Smith's story of his time working on Superman Returns (at that point known as Superman Lives) in the late '90s includes an amusing anecdote about Mr. Peters's demands on what be in the movie, which included not having Superman wear his suit or fly, and to have him fight a giant spider in the final act (Peters's justification being that "spiders are the fiercest killers in the insect kingdom"). The Flash (2023) finally granted Peters's wish by showing the Nicolas Cage Superman fighting a giant spider.
Peters' fascination doesn't even end there: he is known to have requested a mechanical spider be present in a film adaptation of The Sandman (1989) as well. Rumor has it that he was at one point involved in the live-action adaptation of legendary anime movie AKIRA too, which conjures up terrifying mental images of Tetsuo mutating into a giant spider.
Princess of Mars: The Thark patrol which captures is attacked by a pack of giant spiders. John helps to fight them off, there by earning the respect of Tars Tarkus.
Son of Godzilla: Monster Island is home to Kumonga, a spider with a 164-foot leg span. Unlike most of the other examples listed here, she gets a Heel–Face Turn in the next movie in the series, Destroy All Monsters. She shows up again in Godzilla: Final Wars, still shooting her yellow webbing.
The Thief of Bagdad (1940): Abu fights one in a surprisingly suspenseful atmosphere as he climbs a wall, eventually cutting the spider's thread and sending him to a Disney Villain Death.
, but it soon grows out of control until it becomes kaiju-sized.