In The Prison Without Walls episode the heroes find a ramshackle hut in the Swamp of Sorrow and are attacked by three zombies. The zombies are territorial and seem to want to punish the heroes for trespassing in their home. The zombies talk, mainly to reiterate that it is their property.
The In Search Of The Dungeon Master episode has Eric stumble across a man in a swamp and ask him for help before realising he is a zombie. The zombie answers "yes?" to his query and chases him when Eric recoils in horror and runs away.
Zombies are encountered in the Janapurna And The Stallions Of Hokar premise.