In all the world, クレイ (Clay 
, Klay , Cray , among others...) is a common male forename. The given name クレイ is characteristic of Saint Lucia, where it is quite a common masculine name, Tunisia, where it is quite a common principally boy's, but scarcely female name, and the United States, where it is quite a rare male name. In absolute terms, the name is most common in the United States, Tunisia, and the Democratic Republic of the Congo. Likewise, クレイ is the last name as well as the forename.
クレイ is also a popular name for the fictitious and mythical characters: Clay Kaczmarek , the Assassin's Creed character, Assassin's Creed II; Odd Man , the fictional comic book hero created by Steve Ditko; Clay Morrow , the fictional character in the FX television series Sons of Anarchy; Clay Davis , the character from The Wire and Clay Jensen , the fictional character in the novel Thirteen Reasons Why and its television adaptation, 13 Reasons Why, and in many other works.