Principal English Translation: 

the Morning Star; also, Xiuhnel was the name of a Cloud Serpent {mixcoatl) in an origin story studied by Williard Gingerich; Xiuhneltzin was a Chichimec ruler who governed in Temilco; the name Xiuhnel was also taken by tribute payers, such as in the area of Mexico City, held by a man who lived in the city prior to the Spanish invasion) see attestations; it is also regularly attested in sixteenth-century Huejotzingo (contemporary state of Puebla).

Orthographic Variants: 
Xiuhnel, Xiunel, Xiuhneltzin
Attestations from sources in English: 

"And then there came down two deer, each with two heads, and also these two cloud serpents named Xiuhnel and Mimich, who hunt in the Sacred Lands [to the north]." An excerpt from episode two.
Willard Gingerich, https://historicas.unam.mx/publicaciones/revistas/nahuatl/pdf/ecn28/546.pdf.

Xiuhnel is a name attested in the Matrícula de Huexotzinco (c. 1560). See the Visual Lexicon of Aztec Hieroglyphs for the name's visual representations, which typically show turquoise (xihuitl) tesserae or herbs (also translating as xihuitl).

See also: