The first weekend of Pokemon Go was the closest we ever got to world peace.

Final Destination caused an entire generation of drivers to abjectly refuse to take up any space within a quarter mile behind a log truck.

First thing that came to mind is Upton Sinclair's The Jungle which led to, among other things, the creation of the FDA.

That wasn't his goal though; he's quoted as saying: "I aimed at the public's heart, and by accident I hit it in the stomach."

Bugs Bunny changed so much of the world you have no idea. Changed the diet of rabbits because he was making fun of a celebrity. Changed an obscure biblical character into a name for an idiot.

Dr Seuss changed the English language almost as much as Shakespeare.

Also, Shakespeare.

BioShock Infinite accidentally, and indirectly, caused a massive advancement in the animation industry.

Kung Fu Panda changed China's movie industry.

Somwhow, no one has mentioned Lord of the Rings, which basically invented modern fantasy.

The Jungle was a book about the meat packing industry in 1906. It detailed horrific treatment of the animals and disgusting unsanitary treatment of the meat products.

It led to public outrage and caused the Meat Inspection Act to be passed in the same year. That Act laid the foundation for modern health inspections in food facilities.

Star Trek introduced a lot of the first concepts of what we currently use as every day technology, it had a first hand tangible impact on the lives of pretty much every human alive today.

Jurassic Park caused a lot more kids to be interested in growing up to be paleantologists. Ironically, they went on to prove some of the science in the movie wrong

I would argue that Rainman (1988) being a lot of people's first introduction to autism propped up the autistic savant trope

Hackers (1995) did not reflect reality at all, and entirely made up a look, sound and feel of hacker culture for the film. Tech press largely panned it as rediculous, unrealistic and innaccurate, but hacker culture actually morphed into something close to what was depicted in that film because it's honestly way cooler and way better than what the actual hacker culture was at the time

Others have already pointed out really good examples like Upton Sinclair's book The Jungle which spawned a lot of food safety laws, or Wargames (1983) basically prompting the Computer Fraud and Abuse Act

Edit to add: I also remembered another very influenctial author at the turn of the century was Henry George who wrote a now under-discussed book called Progress and Poverty which is widely credited for triggering the beginning of the Progressive Era

In a similar vein, Charles Darwin's On the Origin of Species basically kicked off the entire field of biology with the scientific theory of evolution

Marx, Kant, all of Leibniz' writings. Leibniz needs to be honored more for how ahead of his time he was. Computing algorythms in the 17th century. Mathematics on universe? The last Polymath...

Charles Darwin, On The Origin of Species.

The 24 hour news cycle. It made the news dependent on ratings and turned into an entertainment medium to fill all of the extra hours. Before that, it was a half hour of local news and a half hour of national news at dinner time and at bedtime with snippets of news in the morning on things like the Today Show. CNN created a format, Fox added imaginary outrage, and things went downhill from there.

The Hindenburg crash. If it weren't for the newsreel, it would have been a unique airship crash and the airships would have continued to fly. But because it was shown in every theater as a newsreel for months, the interest in airship travel tanked and fleets were dismantled. It was actually a safe form of travel for the time. While tragic, only 35 people actually died, which is peanuts to a large air liner crash.

Goethe's book "The sorrows of young Werther" caused several suicides of people who emulated the protagonist.

The communicator in Star Trek was an important inspiration for the development of the cell phone and the creators stated that one of their motifs for developing a hand-held telephone was to have something like the Star Trek communicator.

How about war of the worlds radio broadcast?

https://en.wikipedia.org/wiki/The_War_of_the_Worlds_(1938_radio_drama)

The Matrix; check out "the internet" for some examples of its influence.

Surprised the Crying Indian American TV ad isn't in here. I have a giggle when I see someone on here outraged that they saw someone toss trash out their car window. That was SOP until the Crying Indian. I can't think of a PSA in my lifetime that made such a dramatic impact.

While not a piece of media exactly, reporting on the Tylenol Murders changed packaging almost overnight. Used to be you could pull anything off the shelf, open it and close it, no one would be the wiser. I remember as a kid suddenly encountering all the things suddenly having tamper-proof packaging. It was truly wild to my young brain.

A Grand Day Out saved the Wensleydale cheese company when they were on the brink of bankruptcy.

The book Unsafe at Any Speed was partly responsible for the formation of both the US Department of Transportation and the National Highway Traffic Safety Administration.

(Personal case, but i think i am not alone) I have been interested in science since Carl Sagan's Cosmos, i was a kid when it aired.

Anime causes rise in invasive raccoon population in Japan

Dracula and Frankenstein both came out during the same year, 1931. Dracula was so popular in early 1931 that they were able to do all of Frankenstein by the end of the year. Can you imagine?

Those two began the modern era of horror. Modern being not silent.