The alphamegalog of the cities of Texas lists the largest city in Texas for each letter of the alphabet. In this case, ‘largest’ is based on population within the city proper.

Austin
Brownsville
Corpus Christi
Dallas
El Paso
Fort Worth
Garland
Houston
Irving
Jacksonville
Kileen
Laredo
McKinney
North Richland Hills
Odessa
Plano
Quannah
Round Rock
San Antonio
Tyler
University Park
Victoria
Waco
(no X)
Yoakum
Zapata