Grand Unifying Guesses/The Dark Tower

The Dark Tower (and its Beams) takes a different form in every universe. Some of these include:

 * Haruhi Suzumiya, obviously.
 * Azathoth, who lies in the centre of infinity, holding and creating the universe.
 * The Planet Mildchilda, but the Infinite Library especially.
 * The Heart of Kandrakar
 * The Starborn Gem
 * The Door To Revolution
 * The Door Of Light And Darkness
 * The Door Of Truth
 * The Gate Of Truth
 * The Galaxy Cauldron
 * The Star Road
 * The Eye of Harmony
 * The Monarch of Pointland (she takes up her entire universe and thus must be the Dark Tower)
 * The Infinite Clock, the World Tree, and the Sky Tree
 * The aforementioned Tommy Westphall.
 * The Submachine Net
 * Does that make Murtagh Roland? Or Flagg?
 * The Portal Stones
 * Tanelorn
 * Callahan's Crosstime Saloon
 * That fish shop. You know the one, the one they opened on Dagon Street...
 * The fractal key
 * Rupert Murdoch. This would explain a lot.
 * Oban
 * The Gates of Oblivion
 * Spectra
 * The Pillar of Cephiro was the Dark Tower until Hikaru made it so Cephiro was supported by the people of Cephiro.
 * The Ark and the Halo Array
 * That Gate The Gatekeeper is always going on about.
 * And that Other Gatekeeper, too.
 * The Portals from Spyro.
 * The Instrumentality.
 * The Internet in Real Life has the Tower's ability to bridge between realities.
 * The Grand Master Key
 * People's imagination, and to an extension, Imaginationland.
 * The Jewel of Judgment, and by extension, the Primal Pattern. Depending upon interpretation, this may be reversed - the Tower could simply be an image of the Pattern.
 * Witches
 * The Heart of Ponyland
 * And that other gatekeeper and key master.
 * The Shards of Adonalsium. Hoid is busy making sure this version of the Tower doesn't break any further than it already has.
 * Mt. Aleph.
 * The Triforce, with the various Sages/Temples guarding the Beams.