So, back in 1964, the Russian astronomer Nikolai Kardashev came up with a scale for measuring the power and technological advancement of alien civilizations. It had three values: a Type I civilization controlled/consumed power on the order of the total amount of sunlight absorbed by the Earth (10^17 W; this was originally 10^12 W, the approximate power consumption of human civilization in 1964, but was later revised). A Type II consumes power on the order of the total amount of sunlight generated by the sun (10^26 W), and a Type III consumes power on the order of the total combined output of every star in the galaxy (10^27 W).
Noticing that this was almost a logarithmic scale, Carl Sagan later created a revised version. In his version, a score of 0.0 means the civilization consumes 1 MW (10^6 W). Each increase of 0.1 multiplies the power consumption by 10, so a 1.0 is 10^16 W, 2.0 is 10^26 W, and 3.0 is 10^36 W. The advantage of this scale is that it allows relatively easy expansion of the scale and intermediate values.
Now obviously you can argue about the equation of consumption to advancement, which is a very mid-20th-century way of looking at things, but that aside, this scale is really fun to play with.
Japan in Neon Genesis Evangelion is stated to produce a combined output in the hundreds of gigawatts, making it a 0.5.
Human civilization, today, is about a 0.7.
The Enterprise in Star Trek: The Next Generation is stated to have a power output of 12 billion gigawatts, making it a 1.3. This allows us to estimate the Federation’s power output, based on just what percentage of their combined output you think the Enterprise represents. Personally I’d say the Federation is not particularly militarized and the Enterprise is not orders of magnitude more powerful than their other ships, so it’s probably on the order of a thousandth to a ten thousandth of the whole civilization’s power output, putting them no lower than a 1.6 and no higher than a 1.7.
The Super Star Destroyer Executor from the Star Wars movies, on the other hand, is canonically a 2.0, but the Empire is very highly militarized and the Executor is huge compared to their other ships, so I’m guessing it’s about a hundredth of their total output, putting the Galactic Empire at probably a 2.2.
Now let’s get really silly. Silver Age Superman can ignite a star with his heat vision. This definitely puts him somewhere in the 2s, though where exactly is a bit difficult to calculate.
The Iconians of Star Trek Online have thousands of Dyson Spheres, each collecting the entire output of a star. That’d put them at about 2.3.
Humanity in Xenosaga don’t have Dyson Spheres, but the Zohar generates effectively limitless power, enough for trillions of planets in dozens of galaxies. Probably a 2.5 or so.
The Milky Way as a whole is about a 3.1.
A typical quasar is about 3.4.
The Doctor and the TARDIS can, apparently with difficulty, rival a supernova’s output in order to punch a communication through the barriers between parallel universes. That’s on the order of 10^45 W, a 3.9, but they can’t keep it up for long, so they’re probably more like a 3.8.
By similar calculations to the Federation, and remembering that the Doctor’s TARDIS is an old, crappy model, that likely puts the Time Lords as a whole at a 4.2, and the Time War-era Daleks at a comparable level.
The combined output of every star and quasar in the observable universe is roughly a 4.3.
Fans have apparently calculated the energy contained in a Grief Seed to be around 10^55 J. Assuming they collect on average about one every day and a half (~a hundred thousand seconds), that puts the Incubator civilization around 10^50 W, or 4.4.
The observable universe has a mass-energy of about 4 * 10^69 J. The Biblical God is said to have created that in six days (about half a million seconds), for a total of 8 * 10^63 W, which is about a 5.8.
Madoka Kaname dissolved the same universe and rebuilt it from scratch in about 10 minutes (so twice as much work as God in a thousandth the time), giving her about 2 * 10^67 W, a 6.1.
And higher than any of these? Human civilization in Futurama, where a dinky little delivery ship can fly to the edge of the universe in minutes, and an inventor working with the resources of a fly-by-night package delivery service can create and destroy universes on a whim.
Like I said. Silly.