|Appearance||Survival of the Dead|
Seamus Muldoon is a member of the Muldoon family on Plum Island, and a survivor of the undead apocalypse.
When the zombie outbreak occurred, Muldoon's wife turned, and he kept her chained up in the kitchen. Unlike the rival O'Flynns, Seamus and the Muldoons keep their zombified neighbors and loved ones, including Jane O'Flynn, in imitations of their former lives until a cure is found.
Muldoon and Patrick, leader of the O'Flynn family, have a brief standoff which ends with Muldoon exiling Patrick and most of the O'Flynns. When Patrick begins sending survivors from Delaware to Plum Island, Seamus has these survivors killed and fed to the captive zombies.
Three weeks after exiling Patrick, the latter returns to the island with Crockett, Boy, Francisco, Kenny and Tomboy. Later, Seamus and the Muldoons have a standoff with Crockett's group and the O'Flynns on the bridge separating the O'Flynns' and the Muldoons' land, and the O'Flynns are captured. Patrick and Seamus face off, and Muldoon explains to Patrick that his intentions are to get the captive zombies to eat something other than human flesh.
A gunfight erupts between the Muldoons and the O'Flynns, and Seamys shoots the farmhand Chuck when the latter switches sides. Seamus and Patrick, each with one bullet left in their guns, try to declare a truce which Muldoon immediately breaks by shooting Patrick in the back. Dying, Patrick uses a hidden gun to kill Muldoon.
Muldoon then dies and reanimates. The zombified Patrick and Muldoon try to kill each other once more, unaware that their guns are empty.