Genesis Effect

"Simply put: Genesis is life, from lifelessness."

—Dr. Carol Marcus, Star Trek II the Wrath of Khan

Sure, watching planets getting blowed up real good is fun and all, but it takes a lot longer to create something than to destroy it. Sometimes, it's nice to see a world take shape, rather than become rubble.

This trope occurs whenever a planet is born.

Some form of this occurs in every religious Creation Myth. It's also fairly common in Science Fiction. Sometimes it's a naturally occurring event, sometimes someone just possesses the technology to make planets. Typically is used as a symbol for birth and renewal, usually with a hefty amount of Scenery Porn special effects thrown in for good measure, while the sheer amount of energy required can stretch Willing Suspension of Disbelief.

Due to the precarious nature of this trope, writers tend to avoid using it, even when it would be appropriate or interesting to do so.

Contrast Earthshattering Kaboom and Apocalypse How.

Not to be confused with "Blast Processing" on the other Genesis.

Examples of Genesis Effect include:

Comic Books

The High Evolutionary created his own Counter-Earth. It took him six days, then he fell asleep and an evil creation of his tried to corrupt the world.
At one point the canonical source of the Marvel Universe was that Eternity sent Reed Richards back in time to design it. At other times it was caused naturally by a "Big Crunch" of the previous universe or by the Phoenix Force.
In Jack Kirby's The Fourth World the planets of New Genesis and Apokolips were created from the destruction of the planet Urgrund.
After the DC vs Marvel event the two universes were merged into the Amalgam Universe, then split back into the originals.
The Beyonder's "Battleworld" was built out of pieces from many different planets, including Earth from which he took the suburbs of Denver.

Film

Star Trek II the Wrath of Khan: The Genesis Device. Also the Trope Namers.
- And due to the circumstances that it happened in, also becomes a case of Outrun the Fireball
- The plot of the movie is driven by the fact that if the Genesis Device is aimed at a lifeless rock (or nebula), it will create a living, breathing planet... if aimed at a living, breathing planet, it'll erase it entirely and create a brand-new living, breathing planet. Which makes it a weapon of mass destruction as well as mass creation. Subverted; we later learn that Genesis doesn't work. Completely the opposite of its creators' intention, it's only a weapon of mass destruction.
In Titan A.E., the Titan (a giant spaceship) can make a planet out of a comet field almost instantly, with water, oxygen and plants and everything.
- In the novelization, formation of the new planet took almost exactly seven days. Cale thinks his father programmed it to take that long as a joke.
The first part of the "Rite of Spring" segment from Fantasia.

Literature

The Bible. The very first chapter in fact.
The Hitchhiker's Guide to the Galaxy: Magrathea. Where planets are custom-built. Slartibartfast in particular is rather proud of his fjords.

Live-Action TV

During the Doctor Who Christmas Special "The Runaway Bride", the Doctor takes Donna back in time to witness the formation of the Earth.

Video Games

It's almost as easy to create planets in the Space Empires games as it is to blow them up. So easy, in fact, that you can keep destroying and reforming planets if you don't like the atmosphere.
Planets in Master of Orion II can be constructed from asteroid belts or gas giants in already-colonized systems (tough luck with a system that only has asteroid belts or gas giants). They always turn out Barren-class. Since there's no way to terraform Toxic planets, it may be sometimes beneficial to blow up an enemy's Toxic colony with a Stellar Converter, conquer/colonize the neighboring planet, and rebuild the resulting asteroid belt into an improvable Barren world.
In Spore, there are a multitude of different tools for use in making worlds habitable. The easiest to use of these is the Staff of Life, which will instantly transform any planet into a lush paradise, but it only has 42 uses.
Not the funnest part of Dwarf Fortress, or the most dramatic use of the trope, but a world has to be born and grow up a little before play.
The Hungry Lumas from Super Mario Galaxy and Super Mario Galaxy 2, if fed enough starbits or coins, will actually transform into either a new planet or galaxy.

Other

There are a few professional 3D procedural world generation applications, some which render planet-birth to stunning real-time effect similar to Star Trek II.
Every religion or mythology ever has had its version of the Creation Myth.
The formation of the Earth in Real Life makes this literally older than dirt.