Scorponok is the leader of the Decepticon Head Masters. Scorponok is considered a Triple Changer, and he has an additional mode as a city and a base to the Decepticons. He can also transform into a giant robot around the same size as Fortress Maximus whom is also his arch nemesis. Scorponok can also transform into a giant scorpion obviously. He made his very first comic appearance in the original transformers comic series by Marvel in issue #38 (1984-1991). Lord Zarak forms scorponoks head, he is also known as Scorponoks head master component.
There are also another version of Scorponok in comics. He was in the Transformers Energon series done by Dreamwave comics back in 2003-2004. Scorponok is the leader of the Terrorcons. This version wasn't as big as the generation 1 version but he still transforms into a robot and a scorpion but this time instead of transforming into a city or a base he transforms into an aircraft of some sort.
Later a Predacon with a scorpion beast-mode named Scorponok would appear in Beast Wars