Who are The Great Transformers?

The Golden Dawn title for Death is Child of the Great Transformers, Lord of the Gates of Death. Who are the Great Transformers? Who is Death a child of?

The Great Transformers

Maybe time and nature? Book T gives its Brief Meaning of Key 13 as "Time, age, transformation, change involuntary..." Hermetic Tarot's LWB states, "The skeleton alone survives the destruction of time and the aggression of nature, slowly working its way upwards." Then it goes on to give the Book T brief meaning quotes above.
This is my guess... I know I find time and age transformative! ;

That makes sense, the skeleton being the "child."