From TARDIS Index File, the free Doctor Who reference.

Weeping Angel
Appearance / Type:	Winged humanoid
Also known as:	"Lonely Assassin"
Place of origin:	Unknown
Appearances:	DW: Blink WC: A Ghost Story for Christmas
Mentioned in:	DW: The Next Doctor DW: The End of Time

For angels in general, see also Angel.

"Don't blink. Don't even blink. Blink and you're dead. They are fast, faster than you can believe. Don't turn your back. Don't look away. And don't blink. Good Luck."

―The Doctor's warning

The Weeping Angels were a species of winged humanoids from the early universe, so called because they cover their faces, giving them a weeping appearance, to prevent trapping themselves in stone form for eternity. (DW: Blink)

Biology

"You die in the past, and in the present they consume the energy of all the days you might have had, all your stolen moments. They're creatures of the abstract. They live off potential energy."

―The Doctor describing the Weeping Angels.

The Weeping Angels were winged humanoids with sharp teeth who evolved numerous unique survival mechanisms throughout their time, including the ability to move creatures back through time with a touch, allowing them to consume the potential energy from the time the victims could have had alive had the Angels not transported the victims back in time.

There was no apparent reason as to what time period people were transported. Kathy Nightingale was transported to the 1920s; The Doctor, Martha Jones and Billy Shipton were sent to 1969 (DW: Blink); and there was an account of one Julia Hardwick who was transported to 1887 (WC: A Ghost Story for Christmas). The Angels were able to move people through both space and time, as Kathy (and possibly Julia) was touched in London, but ended up in Hull, while Shipton was touched inside a parking garage, but arrived in 1969 in an outdoor location. (DW: Blink)

They also had a unique and nearly-perfect defence mechanism, quantum-locking, which caused them to turn into stone when being observed. When not being observed, they could move incredibly fast to catch their victims. However, this meant that they had to cover their eyes when in their stony form; otherwise if they saw each other they would be trapped forever.

The Weeping Angels also seem to have some psychic abilities as demonstrated when one causes a light bulb to flicker just by pointing at it. This could well mean, though it is left ambiguous, that the Weeping Angels are capable of knowing what is occurring around them while they are in their stone form, as they seemed to be able to know what people were doing around them even when Quantum-Locked.

A Weeping Angel covering its eyes.

History

"Fascinating race, the Weeping Angels. The only psychopaths in the universe to kill you nicely."

―The Doctor

The Weeping Angels evolved near the beginning of the universe, and were the kindest of killers and psychopaths since their method of killing was to let their victims "live to death", but also perhaps the loneliest beings in existence, as due to their defence mechanism they could not even look at each other. In that respect the Doctor appears to pity them.

In 2007, a quartet of Weeping Angels managed to strand the Doctor in 1969 and captured his TARDIS with the goal of using the Time Lord technology for its near-unlimited temporal energy, in a process which is capable of turning off the sun. Despite gaining the TARDIS, the Angels could not find a way into the police box-shaped construct, however they later found the TARDIS's key. Unfortunately for the Angels, Sally Sparrow gained the key from one of the Angels before they could reach the TARDIS by looking at them, causing the quantum locking effect to kick in, leaving a key on one of the Angels for Sally to take.

They then started stalking Sally in their attempt to gain access to the TARDIS. They managed to corner her in the basement of the building where the TARDIS was stored by the Angels, at which point she managed to enter the TARDIS and which dematerialised as the Angels tried to stop it by holding onto it. When it finished dematerialising the Angels gazed at each other across the empty space where the TARDIS was, which turned each other into stone perpetually, thereby ending the group's menace.

It is not known what became of the statues afterward; they could have been left at the Wester Drumlins estate, but seeing as the location was condemned and likely to someday be redeveloped, relocation by the Doctor or another entity is possible.

Because they are turned to stone when observed, any statue in the Universe could have been a Weeping Angel, though most likely just the ones that looked like Weeping Angels. (DW: Blink)

Other References

• Rassilon declared that the two Time Lords who opposed him (who covered their eyes in the same way as the Weeping Angels) were 'monuments to their shame, as the Weeping Angels of old'. (DW: The End of Time)

Behind the scenes

• Although never seen actually moving on screen, the Weeping Angels were in fact portrayed by live actors, as revealed in the episode of Doctor Who Confidential corresponding with Blink. The closest they come to moving on screen is during the sequence in which Sally retrieves the key in the attic at Wester Drumlins: through careful timing, the "statues" subtly change their position while the camera's view is momentarily blocked by actress Carey Mulligan.
• It has been announced by Steven Moffat that the Weeping Angels will return in Series 5.^[1]  They were also seen in a trailer for Series 5.

Footnotes

1. ↑ The Doctor Who News Page - Moffat announces monster return, Tuesday, December 15, 2009 accessed 29th December 2009