|This article is about a/an Dopant identity in Kamen Rider W.|
With the Terror Memory and the prototype Gaia Driver, one can transform into the Terror Dopant (テラー・ドーパント Terā Dōpanto), who can increase the fear in their victims to maddening levels. The user is also shown to be able to use this outside their Dopant form. They can also summon the Terror Field (テラーフィールド Terā Fīrudo) to burn their victims or teleport themself and others across long distances and project their power into their headdress to create a Barong-like creature familar known as the Terror Dragon (テラードラゴン Terā Doragon). However this leads the Dopant more vulnerable to attacks. Although somewhat weakened when using the Terror Dragon, cosmetically noticable through his headdress which changes from blue to brown, the Terror Dopant was still strong enough to overpower Double's basic form.
- Main article: Ryubee Sonozaki
The main user of the Terror Memory was Ryubee Sonozaki (園咲 琉兵衛 Sonozaki Ryūbee), the seemingly wise yet maniacal head of the Sonozaki Family and leader of the Museum. He sported a commanding presence and could adequately terrify many even without the use of his Terror Memory, which was the main reason why the police left him alone even though they have suspicions regarding his activities. He acted as a godfather in the organization and saw the entirety of the city of Futo as his personal kingdom, not letting anyone get in the way of his vision for the city, not even his wife and children. As the head of the Museum, Ryubee oversaw the distribution of Gaia Memories, using those who can use them as research specimens, regardless of the harm and deaths that ensued. He did not seem to consider the Kamen Riders fighting the Dopant crimewave a threat, using the data off of them as a means to perfect his plans for Wakana before turning his attention to regain Philip and complete his plan to initiate the Gaia Impact.
It is revealed that Ryubee was an archaeologist who bought the grounds his estate was built on after finding deposits of fossils and relics beneath it, forming the collection at the Futo Museum where he works as its curator. He eventually discovered the location of the planet's consciousness, dubbed the Gaia Memory (地球の記憶 Chikyū no Kioku), and brought his family to see it. However, when his son Raito fell into the "fountain" of the Gaia Memory and died, but was somehow resurrected by the planet's powers, Ryubee began his plan for the Gaia Impact: an event that would ensure the future of the human race by making them one with the planet itself, much like his son had become. To reach his goal, he used an item dubbed the "Evil Tail" (イーヴィルテイル Īviru Teiru), an archaeologist's brush with the names of his family inscribed on it, to overcome the fear that would go along with sacrificing them to reach his goal, eventually making him go mad. When he sacrificed Raito (Philip) once more into the Gaia Memory to make his daughter Wakana one with the Earth, he was confronted by both Kamen Riders. While Kamen Rider Accel as the AccelTurbuler destroyed his Terror Dragon, Shotaro was able to retrieve Philip's mind and then his body from the aspects of the Gaia Memory in ClayDoll Xtreme to transform into Kamen Rider Double CycloneJokerXtreme to defeat the Terror Dopant and destroy the Terror Memory, along with most of the Sonozaki estate. With Ryubee's mind still broken from years of planning, he enters the still burning ruins of his home, glad that he finally initiated the Gaia Impact. He dies in the blaze, thinking of the good times he had with his family before he discovered the Gaia Memory. 
OOO, Den-O, All Riders: Let's Go Kamen Riders
A copy of the Terror Dopant was one of eight Dummy Inhumanoids, a breed of recreated monsters created by Lem Kannagi of Foundation X, composed of the Museum Dopants and the four main Greeed. The dummy Terror Dopant was fought by Kamen Rider Stronger, who destroyed it with his Stronger Electro Kick.