Scorponok (G1)

Animated series
In the three part Rebith series, Scorponok was a gigantic Headmaster robot built by Zarak, the dictator of Nebulos, upon learning of the Transformers. Lord Zarak has full control of the giant, which was built from an ore processing plant used by the Hive underground. Scorponok itself does not appear to have a mind of its own, though does have a voice separate from Zarak.

Headmasters
The Japanese Headmasters series diverged from Rebirth greatly. In this series, Zarak was one of a group who left Cybertron long ago. In the present day, Zarak led his group of Decepticon Headmasters from his spacecraft, which could transform into the larger Scorponok body.

Marvel Comics
In the comics, Scorponok was a standard sized Decepticon. Upon reaching Nebulos, Scorponok manipulated and blackmailed the politician Zarak into working for him and becoming his binary bonded Headmaster partner.