Jagrafess

The Mighty Jagrafess of the Holy Hadrojassic Maxarodenfoe (often shortened to the Jagrafess or Max) was a creature that appeared in the 2005 revived series of Doctor Who. This monster only ever appeared in a single episode, "The Long Game".

Biology
The Jagrafess appeared to be little more than an enormous mass of amorphous flesh with a mouth filled with many jagged fangs and multiple vestigial eyes all over what could be seen of its body. Though the only vocalisations it made were bestial screeches, it was a sentient being that could possibly communicate to other life-forms via telepathy. It had a three-thousand year lifespan and a rapid metabolism, causing it to generate an excessive amount of heat. The Jagrafess required a cold environment to survive in, otherwise it would rapidly overheat and violently explode.

History
The Jagrafess was put in charge of the ersatz Fourth Great and Bountiful Human Empire in the year 199,909. Away from its home planet, only a facility like Satellite Five could produce enough cold air to sustain it. If no cold air was supplied, the Jagrafess would overheat and explode spectacularly. The heat from Floor 500, where the Jagrafess was installed, was channelled away to the rest of the station, allowing the Jagrafess to remain in a cool climate. Since the Jagrafess could not operate Satellite Five's controls, a human known only as the Editor carried out its orders.

The Ninth Doctor discovered the Fourth Great and Bountiful Human Empire was being controlled by the Jagrafess in 200,000. With the Doctor helping her realise the irregularity of the heating system, Cathica Santini Khadeni used her infospike to channel the heat back towards Floor 500, killing it by causing it to explode.

The Jagrafess itself was a pawn of the Daleks, part of a stratagem spanning several hundred years. After its death, the Daleks went on to other stratagems and renamed the Satellite the Game Station.