The Ilia probe was an avatar of V'Ger, a sophisticated android with the memories of Lieutenant Ilia, whom V'Ger had previously abducted from the USS Enterprise. The probe was designed to interact and inspect the carbon units it saw as infesting Enterprise.

The probe replicated the body of Ilia down to the smallest detail, including pheromones and sweat glands, with molecule-sized microprocessors and billions of connected mechanisms. Even the memory patterns in Ilia's brain were replicated, allowing the crew of the Enterprise to attempt to revive the memories and emotions of the navigator through stimulus.

The Ilia probe was presumably destroyed when Commander Decker merged with V'Ger in order to stop the machine from destroying Earth. (Star Trek: The Motion Picture)