Anime

TVTropes doesn't have anything listed as the origin, but it has a ton of examples if you want to go back in some of the media and see how far it goes back.

The reasoning they give to its popularity is that floating text is easy to animate, can be very flashy for little effort, and can be used as a plot device, with either characters needing time to draw runes, or people refining/debugging their spells, and having something observable to show off the magic power level or the effective range of spells. Basically, it's a really cool, easy, and cheap way to make magic look badass.

As someone's already said, the concept of magical circles/diagrams goes way, way back. But the earliest example I can think of in anime is The Slayers (the first season, which would have aired in the mid-1990s). The interesting bit there is that only a few spells (I think Burst Rondo was one) create patterns there, and when they do show up, they're on the ground, not in front of the caster.

The earliest example I can think of of a magic circle in a JRPG is in the SNES version of Chrono Trigger, where one appears—on the ground again—in a scene where one character is attempting to summon the Big Bad. It's part of the background graphic. Putting something like that in the combat system would have been taxing for the consoles of the era, so if there are any older examples, they're probably also handled as background graphics.

(This is possibly the geekiest post I've made in, um, at least a week?)

Magic circles are all started in 13th century with Kabbalah, and then every kind of text on demon summoning featured esoteric letters arranged into a circle. What's interesting is that the historical alchemy did not use magic circles, but invented a crap-ton of new symbols, subsequentlly adopted in texts on demon summoning.

Surprisingly, DnD does not mention magic circles at all, and in the old fantasy literature (Tolkien, Zelazny, Le Guin etc) the magic is more like voice commands to your Google Assistant, or instinctive abilities like breathing fire - no circles are necessary.

And I guess anime draws magic circles because they look good on screen. Overlord even stacks several circles for an impactful magical sphere.

https://en.wikipedia.org/wiki/Kabbalah

https://en.wikipedia.org/wiki/Key_of_Solomon

https://en.wikipedia.org/wiki/The_Lesser_Key_of_Solomon

Not directly related to anime but to representations of magic in general, but this reminds me of the speed up spell "haste" in Final Fantasy II (PSP) and Final Fantasy X. In FFII, iirc no glyph appears, and the character gets so fast that in the initial peak, he/she runs off to one side of the screen and come back at the other. In X, a glyph appears, but it is a spherical clockwork-like glyph instead.

In a more recent work, now back at anime, magic used by humans in Dragon Raja has audio and visual representations, the voice of the caster distorting, a mist coming out of the caster's moth iirc, and both this mist and the eyes of the caster glowing.

Dragon Raja, apparently making 2D animation in a 3D software, probably is what allows this non-glyph type of representation. By extension, FFX using a 3D engine probably is what allows and even facilitates this type of 3D glyph instead. And FFII, though 2D, is from before the glyph trend, thus preserving the old style.

And this makes me think, maybe the 2D glyphs are used in manga as a way to make easier to represent magic in a purely 2D and static medium, and this ends up causing a habit which evolves to a culture over time.

Curious Archive has a recent video on representation of magic btw, though iirc it's a Nebula exclusive. =/

I wonder if it became popular around the time of Full Metal Alchemist.

Manga Authors have been taking more inspirations from western myth and folklore than they did 40 years ago, particularly the Alchemists who were fond of sophisticated patterns and diagrams, as well as celtic runes and even some Chinese sorcerors.

Didnt this come from Final Fantasy graphics?

For me I think of wheel of time. manipulating the pattern and such.