Eamonn was a terran who served in the Confederate Marine Corps. He saw action during his term of service, but was court-martialed and dishonorably discharged for being drunk on duty. He ended up in "The Gutter" of Tarsonis City, moving on to becoming a snoke addict.
Eamonn is mentioned in the novel StarCraft: Ghost: Nova, which was written by Keith R. A. DeCandido. He may have provided the namesake of Brother Eamonn, who appears in the novelization of Command and Conquer 3: Tiberium Wars, which was also written by DeCandido.