Teruo Suzuki or also known as Arch Orphnoch or Orphnoch King. He is an orphaned boy rescued by Naoya Kaido. Unknown to everyone, he's the most powerful Orphnoch in Kamen Rider 555.
Rescued & Orphaned
An anti-social young boy who was orphaned when his parents died in a fire caused by the Barnacle Orphnoch. Teruo was placed in the Sousai Children's Home (創才児童園, Sōsai Jidōen) orphanage run by Smart Brain until Kaido took him to his home and later stayed and lived in Keitarō's laundry mat, unaware of his immense power.
Rise of Orphnoch King
By episode 45, Teruo began to act strangely and was eventually revealed to be the Orphnoch King in Episode 47. Whenever Teruo blacks out, the Orphnoch persona emerges from his shadow to consume the lifeforce of Orphnoch, in which to fully mature. After being taken by Kiba in episode 50, Teruo eventually transformed completely into the Arch Orphnoch which caused him to die and having the Orphnoch King taking over his body thanks to Kyoji Murakami who fully awakens him by sacrificing his life. Fully awakened, the Arch Orphnoch fully evolved Saeko much to Takuma's fright after beating Faiz. It took Yuji's sacrifice and Faiz Blaster Form's Blaster Crimson Smash to defeat the Arch Orphnoch. But...
After the epic battle between all the riders, it was revealed that the Orphnoch King was powerful enough to withstand the assault from the Kamen Riders. Arch Orphnoch barely survived and was mortally wounded, placed in a stasis tank under Smart Brain's secret facility by the only genetically stable Saeko. Because his fate was never determined, it's unknown will he ever return or remain dormant for eternity.
Kamen Rider Decade: All Riders vs. Dai-Shocker
The Arch Orphnoch have revived and part of Dai-Shocker but was defeated in the final battle.
Kamen Rider × Super Sentai: Super Hero Taisen
Arch Orphnoch was revived as part of Dai-Shocker again. They later united with Dai-Zangyack and battled the army of Kamen Riders and Super Sentai, incluidng Arch Orphnoch's enemy: Kamen Rider Faiz. Faiz and Arch didn't get their own fight scene together, but he was seen fighting TimeYellow and Kamen Rider Super -1, and he is just barely spotted near the end of the second aerial scene fighting Pink5 of Bioman(to see that, you would need it in slow motion and with a high definition picture.) However, his fate, as well as his human identity as Teruo Suzuki, both remained unknown.
Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z
Arch Orphnoch was revived once again and part of Space Shocker. He is killed by Space Sherrif Sharivan.
Kamen Rider Wizard
The Arch Orphnoch was one of Amadum's monsters in the world within the Magic Stone. With the Batta Yummy and Alternatives 01, they attacked and defeated Beast when he intruded in Amadum's lair as he planned to harness the Kamen Riders power, forcing Beast to his proper place in space and time. The three monsters later appeared to capture the young Haruto and Koyomi, fighting off Haruto, Rinko, and Shunpei, when they tried to stop them. They brought the children to Amadum as Tsukasa Kadoya gave him the thirteenth and last Rider Ring (Fourze). The Kamen Riders refused to fight Haruto, saying they fought for human freedom and not just justice, engaging Amadum's monsters. The Arch Orphnoch, Batta Yummy and Alternatives 01, along with several other monsters, were destroyed by Wizard and Decade.
The Arch Orphnoch or Orphnoch King is of a special type who possesses the power to "complete" Orphnoch' evolution, removing all traces of humanity in the process while granting long life. Unlike others, the Orphnoch King can disintegrate them instantly.