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

Appleton
Brookfield
Caledonia
De Pere
Eau Clair
Fon du Lac
Green Bay
Howard
Ixonia
Janesville
Kenosha
La Crosse
Milwaukee
New Berlin
Oshkosh
Pleasant Prairie
(no Q)
Racine
Sheboygan
Two Rivers
Union Grove
Verona
Waukesha
(no X)
(no Y)
(no Z)