tzitzimitl.

See an image that represents tzitzimitl in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).

Ye anquimati yn quitotihui in tocolhuan yn iquac toxiuhmolpiliz ca centlayohuaz hualtemozque yn tzitzimime in techquazque yhuan yn iquac necuepaloz. (Anales de Juan Bautista, f. 8r–8v) = You all know what our grandparents said, that when the end of the year count was tied, that all would become dark and the tzitzimime would come down to eat us. Then many people would be transformed.
Ezekiel G. Stear, Nahua Horizons: Writing, Persuasion, and Futurities in Colonial Mexico (Tucson: University of Arizona Press, 2025), 124–125.

auh ca yehuantin, oquintocayotitehuaque tzitzimime Coleletin, Tzontemoctin in inpan omixeuhtinenque in aquique, tlalticpac tlaca cate Tezcatlepoca, Tlalocan teacuhtli, &c. = They called "tzitzimime," "coleletin" and "tzontemoctin" the [devils] who represented themselves as being those who are people of the earth [with names like] Tezcatlipoca, Tlalocan Tecuhtli, etc.
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 89.

Iztac tzitzimjtl, coztic teucujtlaio, iquetzaltemal. = the white demon of the air was of gold and had quetzal feather balls. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 8 -- Kings and Lords, no. 14, Part IX, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1951), 35.

toztzitzimjtl: muchi coztic teucujtlatl injc tlachiuhtli, quetzallo, iquetzaltemal.
Xoxouhquj tzitzimjtl, quetzallo, muchi coztic teucujtlatl injc tlachiuhtli, iquetzaltemal. = The yellow demon of the air was made all of gold, and had quetzal feathers and balls of quetzal feathers.
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 8 -- Kings and Lords, no. 14, Part IX, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1951), 34.

ca cenca huey tzitzimitl. huey colleletli = a very great demon of darkness, a great fiend (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 1, 82–83.

tzitzimitl = a lesser deity associated with the western sky that could return to earth to torment people
Lisa Sousa, "The Devil and Deviance in Native Criminal Narratives from Early Mexico," The Americas 59:2 (October 2002), 161–179; for quote, see 162. Sousa cites Louise Burkhart, The Slippery Earth, 42–43.

tzitzimimeh = the skeletal supernaturals who appeared during important cosmological transitions...would descend and devour people
David Tavárez, The Invisible War: Indigenous Devotions, Discipline, and Dissent in Colonial Mexico (Stanford: Stanford University Press, 2011), 54.

injc tlaztlacaviaia in tzitzimjtl, in coleletli: mjiecpa monextiaia, moteittitiaia: iuhqujnma ie mocioaquetz, qujnotza, qujmottitia in jnamjc catca: qujtemolia, qujtlanjlia in cueitl vipilli in jxqujch cioatlatqujtl = The demon, the devil, deceived in this manner: many times he manifested himself; he appeared before one like one who had become a mociuaquetzqui; he addressed, he encountered the one who had been her husband; he sought, he demanded the skirt, the shift, all the equipment of women (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 163.

Centlamantli acuetzpali muchiua yn vmpa Egipto, atlan nemi cenca temamauhti yn itlachieliz vel yuhquin tzitzimitl, itoca cocodrillo, yuhquin cuetzpali yc mamaye, auh cenca veytemahmauhti yn ixincayo. Quilmach ceppa cani monamicque coyotl, yhuan ynyn acuetzpali motlatzouilique ytechpa yn intlacamecayo. = The crocodile is an animal from Egypt, frightful in appearance, and monstrous, like a lizard, its skin is frightening with wrinkles and scales, it is huge and misshapen. They say that on one occasion a contest took place between this creature and a fox about the nobility and their ancestral line....(sixteenth century, central Mexico)
Aesop in Mexico: A 16th Century Aztec Version of Aesop's Fables; text with German and English translation, eds. Gerdt Kutscher, Gordon Brotherston, Günter Vollmer (Berlin: Gebr. Mann, 1987), 68.

El diablo del monte. "Salen cinco hombres al monte y un demonio tztzimit se lleva a cuatro de ellos. El quinto, junto con el cura y los habitantes del pueblo, van a una cueva y matan al tzitzimit." (Escuchado en Zaragoza, cerca de Minatitlán, Ver. García de León, 1968, 353–354.)
Fernando Horcasitas, "La narrativa oral náhuatl (1920–1975)," Estudios de Cultura Náhuatl 13 (1978), 177–209, ver 191.

auh ca yehuantin, oquintocayotitehuaque tzitzimime Coleletin, Tzontemoctin in inpan omixeuhtinenque in aquique, tlalticpac tlaca cate Tezcatlepoca, Tlalocan teacuhtli, &c. = á estos llamaron vuestros mayores Tzitzimime, que quiere dezir, feissimos monstruos, Coleletin: dañadas, y asquerosas vestias, Tzontemoctin, aquellos que cayeron del Cielo precipitados assia abajo, con sus espantables melenas.
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 88–89.

ye anq'[ui]mati yn quitotihui in tocolhua[n] yn iquac toxiuhmolpiliz ca ce[n]tlayohuaz hualtemozque yn tzitzimime in techquazque yhua[n] yn iquac necuepaloz = ya saben lo que decían nuestros abuelos, que cuando se atara la cuenta de los años, se iba a obscurecer del todo y bajarían los tzitzimime a comernos y entonces habría una transformación de la gente (ca. 1582, México)
Luis Reyes García, ¿Como te confundes? ¿Acaso no somos conquistados? Anales de Juan Bautista (México: Centro de Investigaciones y Estudios Superiores en Antropología Social, Biblioteca Lorenzo Boturini Insigne y Nacional Basílica de Guadalupe, 2001), 156–157.

"Tzitzímitl es una palabra extendida por gran parte de Mesoamérica, cuya etimología náhuatl es muy incierta; y aunque no resulte incorrecto pensarlas como seres esqueléticos del inframundo y el cielo nocturno, generadoras de vida, para muchos nahuas, hoy día, son también 'malos aires' y 'concentraciones de envidia' que pueden dañar a la humanidad cuando el Sol está ausente. Naturaleza dual de las oscuras entrañas de la tierra, que nutren y devoran, que fue opacada, en el siglo XVI, cuando los evangelizadores utilizaron y difundieron tzitzímitl y coleletli (un vocablo que comúnmente se parea con el anterior) como nombres de demonios."
Berenice Alcántara, "El dragón y la mazacóatl: Criaturas del infierno de un examplum en náhuatl de Fray Ioan Baptista," Estudios de cultura náhuatl no. 36 (2005, 393). Cita a Dakin, Klein, y otras fuentes.