Two new clips have been released for this Thursday’s episode of The Big Bang Theory, previewing Amy’s costume consternation and Howard’s Halloween blues. Plus, news on guest stars both new and very familiar!

Sneak peeks of “The Holographic Excitation” have been released on the net, drumming up even more excitement for The Big Bang Theory‘s Halloween episode. The first clip comes from TVGuide and shows Sheldon and Amy conducting negotiations on a mutually agreeable set of costumes for Stuart’s Halloween party. (Something tells us Amy has the deck stacked against her on this one.)

The second clip shows Howard and Bernadette in all of their succesfully coordinated Smurf-y glory, though all is not sunshine and (pardon us) blue skies for Wolowitz. Watch the clip right here at TVLine.com.

In other news, The Big Bang Theory will keep the guest-stars coming in season six. Astronaut Buzz Aldrin will make a cameo appearance in “The Holographic Excitation”, and Stephen Hawking will lend his voice to “The Extract Obliteration”, airing Nov. 1. CBS says:

Sheldon’s relationship with Stephen Hawking is threatened over a game of “Words with Friends,” and Penny secretly enrolls in a class at the local college.

The following week Levar Burton will appear in “The Habitation Configuration”, joined by no less than Sheldon Cooper’s on-again-off-again arch enemy (say it with us!) Wil Wheaton. The official summary says:

Wolowitz struggles with moving out of his mother’s house. Meanwhile, Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.