Just when you thought you had the Middle-earth family tree close to memorized, along comes the sequel.

So break out your erasers, ye non Fellowship savvy — which should represent, oh, maybe .000001 percent of the audience for The Lord of the Rings: The Two Towers. Towers introduces a parcel full of new characters human, subhuman and otherwise. In no particular order, they are:

Gollum (voiced by Andy Serkis), the deformed, Ring-coveting creature we glimpsed very briefly in The Fellowship of the Ring. Described by some as E.T. gone bipolar, Gollum, it will be remembered, also played a vital part in the J.R.R. Tolkien prequel, The Hobbit.

Theoden (Bernard Hill), the bewitched King of Rohan who later leads a climactic battle at Helms Deep. Other key Rohanians: the King’s niece Eowyn (Miranda Otto), and her brother Eomer (Karl Urban).

Faramir (David Wenham), hotheaded brother of Fellowship member Boromir (Sean Bean), who bit the dust in Fellowship.

Grima Wormtongue (Brad Dourif), horrific and seriously ugly adviser to Theoden. Think he’s evil? Would you name a trusted ally Wormtongue?

Treebeard, an Ent, and the oldest creature in Middle-earth. Picture a humorless walking oak with a serious John Muir complex. He’s voiced by John Rhys-Davies, who also plays Gimli the Dwarf. No, the Ent and the dwarf don’t have any scenes together.

As for our Fellowship, they’re still around but scattered. Hobbits Frodo (Elijah Wood) and Sam (Sean Astin), having splintered off, are on their way to the black gates of Mordor, pursued by Gollum, who serves as a none-too-trustworthy guide.

Meanwhile, studly human warrior Aragorn (Viggo Mortensen), elf archer Legolas (Orlando Bloom) and dwarf Gimli (John Rhys-Davies) encounter the besieged kingdom of Rohan and aid in the unbewitching of King Theoden. Aragorn and Eowyn might make beautiful music together but for Aragorn’s love pact with the elf Arwen (Liv Tyler). The evil wizard Saruman (Christopher Lee) is amassing an army of fighting orcs called Uruk-hai to decimate our heroes at the stronghold of Helm’s Deep.

Having gone staff to muzzle with the unearthly Balrog, Gandalf the Grey (Ian McKellen) is reborn as Gandalf the White.

And finally, hobbits Merry (Dominic Monaghan) and Pippin (Billy Boyd) have escaped their orc captors and spend the bulk of the film in the arms … er, branches … of the Ent, Treebeard, in the Fangorn Forest.