Arthur C. Clarke, mas a ideia era mais antiga.

Aqui está uma citação da página da Wikipedia.

In the 1870s Nikola Tesla, while recovering from malaria, conceived a number of inventions including a ring around the equator, although he did not include detailed calculations. As recounted in his autobiography My Inventions (1919):

Another one of my projects was to construct a ring around the equator which would, of course, float freely and could be arrested in its spinning motion by reactionary forces, thus enabling travel at a rate of about one thousand miles an hour, impracticable by rail. The reader will smile. The plan was difficult of execution, I will admit, but not nearly so bad as that of a well-known New York professor, who wanted to pump the air from the torrid to the temperate zones, entirely forgetful of the fact that the Lord had provided a gigantic machine for this very purpose.[1]

Arthur C. Clarke's novel The Fountains of Paradise (1979) is about space elevators, but an appendix mentions the idea of launching objects off the Earth using a structure based on mass drivers. The idea apparently did not work, but this inspired further research.

Paul Birch published a series of three articles in the Journal of the British Interplanetary Society in 1982.[2][3][4] Anatoly E. Yunitskiy, author of string transport idea, also published a similar idea in USSR in 1982[5] and later explored it in detail in his book published in 1995.[6]

Andrew Meulenberg and his students, from 2008 to 2011, presented and published a number of papers based on types and applications of low-Earth-orbital rings as man's "stepping-stones-to-space". An overview [7] mentions four applications of orbital rings.
_{- Orbital ring - Wikipedia}

Então, a ideia era uma fantasia antes de Arthur C. Clarke, mas ele foi o primeiro a usá-la em uma história.