Mi'en Kalarash
From Tardis Wiki, the free Doctor Who reference
Mi'en Kalarash or "blue fire", was an ancient myth from Gallifrey, said to inhabit "the wasteland between realities". It fed on nightmares. The creature itself was composed of a series of minute slivers in incremental time, a "time magnet". It's outward appearance was a tall, thin humanoid figure with dark leathery skin, a bestial face, all swathed in blue fire. (BFA: House of Blue Fire)