Aaah! A new month, a new episode of CBS’ hit sitcom The Big Bang Theory. Coming up on February 1 is the Sheldon-centric “The Einstein Approximation.”

And I bet Penny is going to be thrilled during the action, too.

In addition to Neil Patrick Harris‘ directorial debut with the new January 18 episode of How I Met Your Mother, CBS’ remaining three Monday-night sitcoms will present new episodes, too.

And featured on Accidentally on Purpose and Two and a Half Men are guest stars Michael Rapaport (My Name is Earl) and Stacy Keach (Titus), respectively.

Wonder Years alumna Danica McKellar guest stars on the new year’s first fresh episode of The Big Bang Theory, January 11th’s “The Psychic Vortex.”

McKellar stops by to portray Abby, a potential romantic interest for adorable yet woman-shy Koothrappali. I hope he gets really lucky.

Acting veteran Christine Baranski, currently a star of CBS’ hit rookie drama The Good Wife, reprises her role as Leonard’s mother Beverly on the new December 14 episode of The Big Bang Theory called “The Maternal Congruence.”

And Beverly is one powerful parent indeed.

Brave Sheldon tackles the seemingly impossible on “The Gorilla Experiment,” the new December 7 episode of The Big Bang Theory.

In an attempt to help Penny better appreciate what Leonard does for a living…

First it was Tricia Helfer on the November 16 episode of the hit CBS sitcom Two and a Half Men, and now it’s her fellow former Battlestar Galactica colleague Katee Sackhoff guest starring on the fresh November 23 “The Vengeance Formulation” episode of CBS’ other hit sitcom The Big Bang Theory.

The actress many know best as Starbuck makes a cameo appearance as the woman of Wolowitz’s dreams, which isn’t exactly an enviable position.

Penny gets some unlikely assistance on “The Adhesive Duck Deficiency,” the brand-new November 16 episode of CBS’ The Big Bang Theory.

When everyone’s favorite resident female is injured…

Sheldon comes between two lovers during “The Guitarist Amplification,” the fresh November 9 episode of The Big Bang Theory.

The lovers in question are Leonard and Penny, of course.

Sheldon shocks us all during the November 2 episode of The Big Bang Theory called “The Cornhusker Vortex.”

While the world’s most non-athletic dude ever teaches Leonard a thing or two about…

The Big Bang Theory gets its geek on big time during the October 19 episode “The Creepy Candy Coating Corollary,” which features guest star Wil Wheaton (Star Trek: The Next Generation) in a cameo.

Although he plays himself, it turns out Wil happens to be a hated rival of Sheldon, who’s determined to settle an old score.