Onion Knight FFIII

Onion Knight (seemingly based on the lead character of the NES version, but with an alternate costume based on Luneth) and the Cloud of Darkness are the respective hero and villainess representing Final Fantasy III in Dissidia: Final Fantasy, where they are voiced by Jun Fukuyama and Masako Ikeda respectively in the Japanese version.
The Cloud of Darkness is referenced in Ivalice-set titles Final Fantasy XII, Final Fantasy Tactics Advance and Final Fantasy Tactics A2: Grimoire of the Rift as a summonable entity (known as an "Esper" in the first, a "Totema" in the second and a "Scion" in the third) by the name of Famfrit, also known as "the Darkening Cloud".