Dr. Horrible's Sing-Along Blog: Who's Who?

Now that you've got the basics, hit the comments with all of your horrible thoughts!

Neil Patrick Harris

YOU KNOW HIM AS: Barney Stinson — How I Met Your Mother's womanizing, self-aggrandizing, somewhat deluded yet all-around awesome purveyor of the Bro Code

HERE HE PLAYS: Dr. Horrible — a wannabe evil mastermind with “a Ph.D. in horribleness,” a desire to destroy Captain Hammer and a debilitating crush on do-gooder Penny; those not attuned to the evil underground know him as Billy

EXTRA HORRIBLE TIDBIT: Horrible's Death Ray is actually a repurposed prop from Firefly, turned upside down and embellished a little.

Nathan Fillion

YOU KNOW HIM AS: Rick Castle — Castle's author of mysteries, consultant on police cases, poker player and new love interest of a certain lovely lady cop

HERE HE PLAYS: Captain Hammer, a not-so-sharp, self-involved doer of good; also, Dr. Horrible's chief nemesis

EXTRA HORRIBLE TIDBIT: In Dr. Horrible's sung DVD commentary, Fillion performs an entire song about how he's better than co-star Harris. Sample lyric: “He makes seven figures and gets Emmy nods, I make seven layer bean dip of the gods.”

Felicia Day

YOU KNOW HER AS: Holly Marten — Eureka's rocket scientist, who showed up in several iterations throughout the sci-fi series; she's also Codex in The Guild, the Web series she created, and she's appeared in other Joss Whedon projects like Buffy the Vampire Slayer and Dollhouse

HERE SHE PLAYS: Penny, a quiet woman looking to make her city a better place, particularly through her volunteer work at a local soup kitchen/homeless shelter

EXTRA HORRIBLE TIDBIT: On her Web site, Day notes that the soundtrack's success “made me a Billboard Top 40 artist, which makes me giggle with the absurdity of it.”

Simon Helberg

YOU KNOW HIM AS: Howard Wolowitz — The Big Bang Theory's bowl cut-sporting aerospace engineer who recently became both a husband and an astronaut

HERE HE PLAYS: Moist, Dr. Horrible's perpetually sweaty henchman

EXTRA HORRIBLE TIDBIT: Though unfamiliar with Joss Whedon's work, Helberg told the Huffington Post he took the gig because he knew Zack and Jed Whedon (Joss' bros, who co-wrote the project with him and Jed's wife Maurissa Tancharoen) from high school.

Now that you've got the basics, hit the comments with all of your horrible thoughts!

Neil Patrick Harris

YOU KNOW HIM AS: Barney Stinson — How I Met Your Mother's womanizing, self-aggrandizing, somewhat deluded yet all-around awesome purveyor of the Bro Code

HERE HE PLAYS: Dr. Horrible — a wannabe evil mastermind with “a Ph.D. in horribleness,” a desire to destroy Captain Hammer and a debilitating crush on do-gooder Penny; those not attuned to the evil underground know him as Billy

EXTRA HORRIBLE TIDBIT: Horrible's Death Ray is actually a repurposed prop from Firefly, turned upside down and embellished a little.

Nathan Fillion

YOU KNOW HIM AS: Rick Castle — Castle's author of mysteries, consultant on police cases, poker player and new love interest of a certain lovely lady cop

HERE HE PLAYS: Captain Hammer, a not-so-sharp, self-involved doer of good; also, Dr. Horrible's chief nemesis

EXTRA HORRIBLE TIDBIT: In Dr. Horrible's sung DVD commentary, Fillion performs an entire song about how he's better than co-star Harris. Sample lyric: “He makes seven figures and gets Emmy nods, I make seven layer bean dip of the gods.”

Felicia Day

YOU KNOW HER AS: Holly Marten — Eureka's rocket scientist, who showed up in several iterations throughout the sci-fi series; she's also Codex in The Guild, the Web series she created, and she's appeared in other Joss Whedon projects like Buffy the Vampire Slayer and Dollhouse

HERE SHE PLAYS: Penny, a quiet woman looking to make her city a better place, particularly through her volunteer work at a local soup kitchen/homeless shelter

EXTRA HORRIBLE TIDBIT: On her Web site, Day notes that the soundtrack's success “made me a Billboard Top 40 artist, which makes me giggle with the absurdity of it.”

Simon Helberg

YOU KNOW HIM AS: Howard Wolowitz — The Big Bang Theory's bowl cut-sporting aerospace engineer who recently became both a husband and an astronaut

HERE HE PLAYS: Moist, Dr. Horrible's perpetually sweaty henchman

EXTRA HORRIBLE TIDBIT: Though unfamiliar with Joss Whedon's work, Helberg told the Huffington Post he took the gig because he knew Zack and Jed Whedon (Joss' bros, who co-wrote the project with him and Jed's wife Maurissa Tancharoen) from high school.

Now that you've got the basics, hit the comments with all of your horrible thoughts!