Zombie titans.
Hordes sometimes condense into a single being with unlimited height and size. Comes in 2 types
Composite: each individual zombie remains intact, and they just lego themselves into a larger zombie
Biomass: the zombies are only used for their parts and mass. Same as any other living creature the titan eats. Basically a super blob with zombie parts for armor and utility/abilities. including spitters, screamers, necromancers, and shockers. Only zombies absorbed or evolved inside them count towards this though. Or not, whichever.