yehuatl.

Headword: 
yehuatl.
Principal English Translation: 

he, she, it, they, etc. (see Karttunen); that, that one (see Molina)

also: someone; what
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 68–69. (17th c., central Mexico)

Orthographic Variants: 
hehuatl, llechuazi
IPAspelling: 
yehwɑːtɬ
Alonso de Molina: 

yehuatl. aquel, aquella, aquello.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 35r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

(Y)EHHUĀ-TL pl: (Y)EHHUĀN ~(Y)EHHUĀNTIN he, she, it, they, etc. (independent third person pronoun) / aquél, aquella, aquello (M) This is the long form of the third person referent YEH~EH. It sometimes appears as EHHUĀ-TL, but YEHHUĀ-TL is more common. This also appears without the absolutive, and when honorific-TZIN is attached, the absolutive is not used. See (Y)EH. EHHUĀN See (Y)EHHUĀ-TL.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 338.

Lockhart’s Nahuatl as Written: 

he, she, it, that. independent pronoun. shortened forms yehhua, yeh. reverential yehhuātzin. yehhuātl īn, this. yehhuātl ōn, that. abs. pl. yehhuāntin
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 242.

Attestations from sources in English: 

Mi Señora de Guadalupe yhua yechuatzin S.r de Chalma = mi señora de Guadalupe and the Señor de Chalma (Calimaya, Toluca Valley, 1712)
Caterina Pizzigoni, ed., Testaments of Toluca (Stanford: Stanford University Press and UCLA Latin American Center Publications, 2007), 209.

huel yehuatl = that very person
Robert Haskett and Stephanie Wood's notes from Nahuatl sessions with James Lockhart and subsequent research.

auh yehuatl yc mochallanique = and what they argued about (early seventeenth century, central New Spain)
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 66–67.

llehuazi = yehuatzin (referring to a brother, Valley of Toluca, 1756) Caterina Pizzigoni, ed., Testaments of Toluca (Stanford: Stanford University Press and UCLA Latin American Center Publications, 2007), 114.

llechuazi (San Juan Bautista, Toluca Valley, 1784)
Stephanie Wood collection, notes in a folder about Bills of Sale; citing AGN Tierras 2301, exp. 10, ff. 5r.–6v.

yèhuātl = he, she, it (third person independent pronoun) (colonial Mexico)
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 9.

llehuatzin nosubrinotzin Dn Martin Gregorio = my nephew don Martín Gregorio (Toluca valley, 1822)
Miriam Melton-Villanueva, The Aztecs at Independence: Nahua Culture Makers in Central Mexico, 1799–1832 (Tucson: University of Arizona Press, 2016), 176–177. Note the use of ll for y, a late phenomenon.

Yehhualt (Yancuictlalpan, Toluca valley, 1810)
Miriam Melton-Villanueva, The Aztecs at Independence: Nahua Culture Makers in Central Mexico, 1799–1832 (Tucson: University of Arizona Press, 2016), 185. The reversal of the -tl ending is notable here.