Leyor was a Caldonian who worked as a diplomat and negotiator in the mid-24th century.

In 2366, he participated in negotiations on board the USS Enterprise-D over the rights to the newly-discovered Barzan wormhole.

Leyor eventually withdrew the Caldonian bid for rights to the wormhole when it became clear to him (with a little "help" from the empath Devinoni Ral) that the administrative demands of maintaining the wormhole would detract from their ability to conduct research. Leyor subsequently agreed to sell the Caldonians' rich deposits of trillium 323 to the Chrysalians who were represented in the negotiations by Ral. (TNG: "The Price")

Leyor was played by late actor Kevin Peter Hall in his only Star Trek appearance. Tony Todd also auditioned for the role.
The script for "The Price" states the pronunciation of Leyor's name as "LAY-or". Furthermore, it describes the character as "...reserved -- with a quietness that comes more from academia than from shyness." [1]
Regarding Leyor's etiquette, he referred to both Deanna Troi and Bhavani as "Madame" (pronounced French).
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