Boekind

Boekind was a species from the Silver Devastation in the Isop Galaxy.

Biology
Boekind were large, humanoid heads with numerous tendrils which terminated in round pod-like structures in place of hair. (DW: The End of the World)

Boekind can communicate telepathically and are able to speak, though they more commonly prefer telepathy. (DW: The End of the World, New Earth, Gridlock)

In Gridlock Thomas Kincade Brannigan spoke of a myth of a woman who breathed in the noxious fumes of the motorway for twenty minutes. Supposedly her head swelled up to fifty feet. This myth could be influence by the Face of Boe who is basically a giant head who survives by breathing gas.

Life Cycle
Little is known about Boekind reproduction, but it is known that they could become pregnant and give birth. The actual minimum and maximum of young per pregnancy is unknown, but the Face of Boe gave birth to six children. (DW: The Long Game)

Technology
The only technology known to be used by Boekind was a life support tank with added teleport in which the Face of Boe lived in permanently, however even this may be not have been created by Boekind and may be a creation of another race. (DW: The End of the World, New Earth, Gridlock)

History
The first of Boekind, the Face of Boe, may have been Jack Harkness. After the Battle of the Game Station, the Bad Wolf entity made him near-immortal. Eventually, he started to age, albeit very slowly. The ultimate outcome of this was possibly the Face, so named because that was one of Jack's nicknames, as he was born on the Boeshane Peninsula. (DW: Last of the Time Lords)


 * Presumably, Jack time traveled back to the Dark Times, as Boekind were known as an ancient species, having originated in the Isop Galaxy "when the stars of the Andromeda galaxy were still dust". (DW: Bad Wolf)

In the year 200,000, the Face gave birth to six children, the Boemina, although in 40 years time even the Boemina would die (DW: The Long Game). The Face later nearly died in the year 5,000,000,023 but managed to survive (DW: New Earth), but later sacrificed himself to save the inhabitants of New New York in the year 5,000,000,053. (DW: Gridlock)

Rather more suitably, The Face of Boe may be merely an evolutional form of Captain Jack Harkness, possibly removing most of the "impossible" properites of the Captain. Or, it might even be suggested that the Doctor will venture back to Boe, to strip these properties.