[cfmcdonald]

It looks like the trend started circa the 1920s in the U.S. Kotex (1920) [0], Kleenex (1924) [1], Kool-Aid (1927) [2], Kool (1933) [3], Krispy Kreme (1934) [4].

Kraft might look like one, but isn't, it's named after James Kraft [5], which presumably traces back to the german word Kraft.

I'm curious if there are older examples.

[0]: https://en.wikipedia.org/wiki/Kotex [1]: https://en.wikipedia.org/wiki/Kleenex [2]: https://en.wikipedia.org/wiki/Kool-Aid [3]: https://en.wikipedia.org/wiki/Kool_(cigarette) [4]: https://en.wikipedia.org/wiki/Krispy_Kreme [5]: https://en.wikipedia.org/wiki/James_L._Kraft

[Rendello]

Not a brand name, but "ok" is widely believed to be from a meme from 1838 where abbreviations were comically misspelled. "Ok" being "Oll Korrect":

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