Dawn Of An Era is when the story has a moment that will change the story world in a good way.
For instance, someone, at great personal risk, not only successfully tests a practical and reliable way to travel to different solar systems as easily as sailing across the Atlantic, but aliens detect that trip and decide to pop by to say, "Welcome to the neighborhood!"
Suddenly, all realize that their lives, their world and their very view of the universe has changed forever with marvels, technology, magic, and astounding possibilities and challenges lying before them to persuade even the most despairing soul to have faith of the heart for a glorious future.
Thanks to the heroes, a brave new world has begun where the age of wonders is just beginning.
(Err, not the bad one, we promise!)
For the villainous version, see New Era Speech. For the complete opposite, see End of an Age. For a related trope, see The Magic Goes Away.
The conclusion of Transformers Cybertron. The Autobot/Decepticon war is over, the universe is saved, Cybertron is healed, the lost colonies have been brought back into the fold, and Transformers and humanity work side-by-side to explore and connect the galaxy.
In One Piece, the Pirate King, Gold Roger, ignited the Golden Age of Piracy with his death.
This and the End of an Age occurred at the same time at the tail end of the Marineford Arc. Just when his death and a marine victory was poised to snuff out the Golden Age of Piracy, Whitebeard, with his dying breath, proclaimed, with the entire world watching, "ONE PIECE EXISTS!" This proclamation started an entirely new age of piracy, and the beginning of a new era. However, just minutes later, Blackbeard (the probable Big Bad of the series) makes his own declaration: that the new era that's dawning is his era.
The opening scenes to Mobile Suit Gundam Unicorn shows the very beginning of the Universal Century, which is meant to evoke this trope Until it gets rudely interrupted by the space colony said scenes take place on being blown up.
The three issue Comic BookVimanarama has the epic of Ben Rama as real, with super science instead of magic. After the evil Ul-Shatan is defeated, the world is transformed with access to ancient philosophical truths, flying vimanas, vitamin laden air, prayer fueled refrigerators, and other marvels. The series ends with the hero rescuing three young idiots who crash a two man flying vimana into the bright face of the moon.
The first public appearance of Superman in the DCU. In most continuities, Superman is first introduced the world doing a dramatic save, giving the world something to hope for and kicking off the Age of Superheroes. (Or bringing back superheroes, in the Golden Age heroes are in continuity).
Likewise, his return in Kingdom Come is this for everyone but The Narrator (who foresees that this will be a subversion instead). However, The Narrator talking down Supes in the end is the real dawn of an entirely new era.
In the film version, the closing narration makes it clear that this has motivated the nations of the world to end their conflicts.
Star Trek: First Contact: The crew of the Enterprise foil the Borg back in time and help Zefram Cochrane make his famous test flight of The Phoenix, the first warp-capable Earth craft. As a result, an alien ship detects the ship and decides to initiate first contact. When they appear from their landing craft and reveal themselves to be Vulcans, you know that Earth's time of planetbound turmoil and despair is over, and the planet's vibrant and hope-filled future as a space power has begun. Jerry Goldsmith's score complements it beautifully, too.
Transformers The Movie ends with the Autobots in charge again and Rodimus Prime predicting an era of peace and prosperity for all Cybertronians.
Rodimus: Let this mark the end of the Cybertronian Wars as we march forward into a new era of peace and happiness! 'Til all are one!
In Echoes of the Fourth Magic, nuclear war leads to an end of modern civilization. Angelic beings rescue some of the humans, however, and the world is born anew with magic and fantasy creatures.
In Courtship Rite, the discovery and decryption of the ancient document, The Forge of War, gives the Getans new insight into their history, and information about all sorts of useful Lost Technology.
Live Action Television
The Babylon 5 episode, "Into the Fire" where Capt. Sheridan leads a united force against both the Vorlons and the Shadows. Where at the beginning of the series, G'Kar notes the younger species of Humans, Narns etc. could no more interact with their predecessors than ants could with them, now Sheridan is able to tell two such god-like species to vamoose. Both races decide to leave, and the Third Age has begun where the younger species now live on their own terms, free of such godlike interference. This example mixes in a bit of sadness, as the departing Precursors take a great deal of wonder with them as well.
As well as a bit of dread, now that the "grownups" are not around anymore to bail them out. Cue the Thirdspace movie, where they stumble upon a Sealed Evil in a Can that the Neglectful Precursors left behind.
The very first words, spoken in voiceover by Londo Mollari at the opening of the pilot episode, were: "I was there at the dawn of the Third Age."
For an example that isn't an ending, the premise of Earth: Final Conflict is that aliens have come and helped transform the world for the better, offering solutions to famine, disease, and other ills free of charge. Not only were they not here To Serve Man, and more amazingly, we didn'tattack these peaceful aliens. However; something fishy was afoot, and you don't want to know what. Trust us, it's better if you ignore seasons 2+.
As does Final Fantasy XIII. To elaborate, XIII covers the end of Cocoon, where fal'Cie ruled humanity and the birth of a new human civilization on Gran Pulse, free of fal'Cie (and particularly Lindzei's) rule.
The end of God Of War III has this and an End of an Age. The age of Greek Myth, with its gods and monsters all dead, is over and the world is on the brink of ruin. Even the Fates are gone. But in his final moments, Kratos released the power of Hope, a power great enough to kill gods, to humanity. The survivors will be able to rebuild civilization free of the gods' influence and as masters of their own destiny.
Mass Effect 3 has an opening crawl in which First Contact between humanity and the many other species of the galaxy is said to be one of those - yeah, it did start with a short and brutal war, but it was called off quickly, and thirty years later humans and turians are sort of Vitriolic Best Buds. Then the Reapers came to ruin everything. The endings, particularly in the Extended Cut, can show another dawn on a much larger scale, if Paragon Shepard really hauled ass. The krogan may have started their cultural renaissance, moving beyond brutishness. The quarians and geth may share Rannoch peacefully. Depending on the ending, the Reapers might be part of it too.
In Real Life some members of the Transhumanist movement believes that we currently live just on the brink of the Technological Singularity, which is to put an end to most problems that plague the modern society (but potentially create a ton of new ones), and usher the age of immortal, superhuman cyberminds.
In The Wheel of Time, this is combined with End of an Age; while the current Age is coming to an end, a new one is beginning, new Talents of the Power are being discovered, and vast advances in technology are being made. One character even lampshades it while watching a demonstration of the world's first ever cannon: "The world just changed in a very big way."
The great conflict of Golden Sun: The Lost Age, over whether to restore the power of Alchemy to the world and risk it falling into the hands of evildoers or to let the world rot without Alchemy, is ultimately resolved in favor of restoring Alchemy by the heroes. The Lost Age ends on a relatively hopeful note: the parents come back, Alex's plans to gain the power of the Golden Sun are thwarted, and now the world can return to its former glory, right? Golden Sun Dark Dawn begins thirty years later and stars the Spin Offspring... fighting new evils powered by Alchemy and newly-restored ancient Magitek. Oh, and Alex is alive and well as a demi-god.
The ending of Kingdoms Of Amalur sees the end of Fate. Together with the surge of magical potential among the mortal races marks the beginning of the Age of Heroes. It's not all good news though. The Fae and their magic are also slowly fading from the world. The Great Cycle has been broken, rendering them mortal for all intents and purposes. Many of the Fae encountered in-game know all too well that their time has passed.