Elizabeth Norment, who played Nancy Kaufberger, died between seasons 2 and 3.
Reg E. Cathey died shortly after production began on Season 6, though it's unknown if Freddy was intended to appear as his final scene telling Frank off back in Season 4 gave a decent closure to his arc.
Career Resurrection: For Robin Wright, who had spent most of the 2000s in supporting or background roles in independent movies. House of Cards offered her a co-lead role in a mainstream product for the first time in several years, earning her a Golden Globe award as well as multiple Emmy nominations in the process. She was subsequently in more big-budget features (like Wonder Woman (2017) and Blade Runner 2049) as a result.
Directed by Cast Member: In addition to playing Claire, Robin Wright has directed seven episodes of the show.note Chapter 23 in season 2; chapters 35 and 38 in season 3; and chapters 42, 43, 48, and 49 in season 4
Fake American: English Jayne Atkinson as Catherine Durant; Swedish-American Joel Kinnaman as Will Conway.
Fake Brit: Irish Dominique McElligot as English Hannah Conway.
Fake Nationality: Fake Hispanic: Indian-American Sakina Jaffrey as Hispanic-American Linda Vasquez.
Name's the Same: Rather bizarrely, Doug Stamper is the only character to have the same last name as their British counterpart (Tim Stamper). Similarly, Francis Underwood is the only character to have the same first name as his British counterpart (Francis Urquhart), and Claire also always addresses him as "Francis"; everyone else addresses him as "Frank" because a Southern Gentleman named Francis would insist that you call him 'Frank', and a British aristocrat would faint at the idea.
Reality Subtext: It's pretty much impossible to not see the scene in the series finale where Stamper claims he killed Frank because "I couldnt let him destroy everything we built; I had to protect the legacy from the man" as a meta-commentary for what Netflix did by firing Kevin Spacey from the show and killing off his character due to his sexual assault allegations.
Michel Gill (President Garrett Walker) is married to Jayne Atkinson (Secretary of State Catherine Durant).
Paul Sparks' (Thomas Yates) real-life wife Annie Parisse appears as a mother on the Iowa campaign trail.
Michael Kelly's (Doug Stamper) real-life daughter Franke and son Clinton make an appearance in Chapter 36 as Doug's niece and nephew. They even have the same names.
Role-Ending Misdemeanor: Almost like Show-Ending Misdemeanor. After actor Anthony Rapp accused Kevin Spacey of molesting him when he was 14, Netflix first announced that the show would conclude with season six. They then suspended production on the season and fired Spacey after more accusations of sexual harassment and assault came out, including, most damningly, some from the set of the show itself. It was eventually decided that the show's sixth and final season would be completed with Robin Wright as the sole lead.
Separated-at-Birth Casting: Kelly AuCoin, who plays Doug Stamper's brother Gary, seems to have been cast because he looks like a spitting image of Michael Kelly.
Troubled Production: Filming on Season 6 was interrupted by Anthony Rapp's accusation that Kevin Spacey molested him 30 years earlier, when he was fourteen. Netflix quickly announced that this would be the show's final season (though this was always the plan anyway), and shortly afterward shut down production indefinitely as similar stories about Spacey came pouring in. He was then sent for an unspecified "evaluation and treatment," throwing further doubt on whether the season would be completed. And then eight crew members came forward with accounts of Spacey's predatory behavior which made them deeply uncomfortable around him. Spacey was fired a week later. In the end, production on Season 6 resumed with Robin Wright becoming the sole lead.
When Frank Underwood visits Petrov in the Jordan Valley in Chapter 36, the Navy SEAL security team riding in the Hummers with him are all real Navy SEALS that Kevin Spacey worked with on Captain Phillips (on which Spacey served as an executive producer). In particular, the Navy SEAL on his immediate left when Frank steps out of the vehicle is Spacey's actual bodyguard in real life.