Mad Goat of the Fens

The Watcher is generally considered to be the only known ancient evil. Here is his flavour text:

"Imprisoned by Connacht during the Wind Age, the Watcher only escaped by tearing off his left arm at the elbow, like a wolf chewing through his leg to escape a snare."

This shows that the Watcher is indeed ancient as he was alive in the Wind Age and was fighting Connacht, the Light hero of that age. We are given more info on the Watcher in the Journal entry for Silvermines...

"The old stories all tell that when Balor freed The Watcher from his prison under the Cloudspine, one arm was left trapped in his prison of solid rock."

...and the Deceiver's Myth 2 flavour text:

"The Watcher had been the second or third most powerful sorcerer in living memory"

This is backed up when we hear of the avatara Mazzarin and his defeat by the Watcher in Alric's flavour texts:

" Of all the avatara in the Four Ages there is no doubt that Mazzarin was the most powerful and his death the most salient victory of the Dark during the Wind Age."

" ... the seventh wave of Thrall stumbled and climbed over the slippery, piled dead and Mazzarin saw The Watcher with them and at last knew the number of his days."

The Dissapearing Shade

An un-used STLI clip in the artsound.gor file (which presumably would have a corresponding sound) says "What the hell - where did he go?" on the TFL level: "The Watcher". Originally it was thought that this was said when the Watcher was killed but in fact it happens when the first shade teleports. Teleports? Yes, the first shade was supposed to teleport out before he dies and then reappear where the second shade (Mazzarin) currently appears. It is still possible to trigger the teleportation routine. If you can get to the second shade without killing the first, the first one will vanish as the second appears. AMythmaster film demonstrates this, but there's still no "where did he go" played

(Thanks go to Forrest for correcting me on this one.)

But is the Watcher Dead?

After the berserks destroy the Watcher in the TFL level The Watcher, we never see him again. Is this proof of his death?

DarkSword has this to say about it:

Somehow when the watchers body was turned to stone it became sort of a 'shell', since the fallen knew that he wasn't dead and could be freed by simply breaking the stone encasement around it, they 'allowed' the 100 volunteers to 'try' to reach the watcher and shatter his entrapment. Probably the fallen lords could have cared less whether the light made it to the Watcher or not, but I imagine they'd rather sacrifice light units when the watcher escapes his stone trap (i.e. when the zerks shatter his body it blows up and may kill a few of your men)... anyway the point is the watchers stone body was just a lure and in any event the fallen knew the watcher would survive, and decided they might as well kill a few zerks on the side.

So, did the arrows not have the desired effect? Was the Head merely deceiving Alric and the legion all along? Probably

The Arm

A long while ago, ThorulfR made a remarkable discovery.

In the Watcher's unit description

"...the Watcher only escaped by tearing off his left arm at the elbow..."

And sure enough, every time we see the Watcher's arm, it is indeed a left one.

However, the Watcher himself is missing the right one.

This discrepancy sparked a series of discussions at the Asylum which produced two points of opinion. The first; that the Watcher still lives and that the one we kill is a fake, was met with the second; that the Watcher is truly dead and the artwork was only a mistake.

To find an answer to this riddle, Forrest Cameranesi decided to go to the source and ask Bungie themselves. Read the response he got on the Asylum

But he wasn't going to leave it at that so he followed it up with a more direct email to three big men at Bungie. See what Doug Zartman had to say at the Asylum

Based on the first message, I came up with a theory of my own:

The arm found by the Legion in Silvermines was actually not the Watcher's but a decoy set by the Fallen to lure Alric to Silvermines and then to stall them with the Watcher. However, the decoy failed and the Watcher was killed thus allowing the Legion to continue North and escape the pursuing Soulblighter.

I take the second message as simply a decoy to cause nothing but confusion and as a promotion for the Total Codex, the latest Bungie release at that time.