Dr. Judith Mossman is a scientist who plays an integral role as the personal assistant for Dr. Wallace Breen, effectually becoming his second in command. However, Mossman was in fact a cunning and manipulative triple agent, aiding both sides during the Uprising but eventually siding with the Resistance against the Combine. Mossman has a friendly if cunning personality, tempered by a certain amount of arrogance. She does not get on well with Alyx Vance.