Sometimes you catch an episode of television that you want to watch again and again because an individual's performance is simply brilliant.
The actors found below did something special in the episodes, and for the reasons noted, they've made our list for 2015.
Weigh in with your thoughts in the comments!
1. Bellamy Young as Mellie Grant - Scandal Season 5 Episode 9, "Baby it's Cold Outside"

Her epic filibuster had nothing to do with Fitz or Olivia or anything like that; it was all about protecting the rights of women. It didn't matter that it was Christmas Eve, that she was wearing heels, or that she really had to pee. She did what she had to do, and it worked. It was inspiring and incredibly well done.
2. Elizabeth Henstridge as Jemma Simmons - Agents of SHIELD Season 3 Episode 5, "4,722 Hours"

Watching her hold onto her optimism and hope for so long and then seeing the realization hit her when she loses it was absolutely heartbreaking. Henstridge's performance was so captivating that it was easy to forget the rest of the regular characters weren't around.
3. Joelle Carter as Ava Crowder - Justified Season 6 Episode 13, “The Promise”

But leave it to Ava to play both sides and ditch both men in favor of her own future. It was a high wire balancing act leading up to Justified Season 6 Episode 13, “The Promise” that left us guessing until the very end. Through it all, Carter showed us Ava’s combined determination and vulnerability in an amazing performance that won’t soon be forgotten.
4. John Noble as Morland Holmes - Elementary Season 4 Episode 6, "The Cost of Doing Business"

That is, up until the end of Elementary Season 4 Episode 6, when Morland cold-bloodedly threatens the life of a would-be blackmailer, and suddenly it's all to easy to see why people are just so scared of this man. Noble is absolutely brilliant in the role, and he absolutely elevates every scene in which he appears.
5. Peter Capaldi as The Doctor - Doctor Who Season 9 Episode 11, "Heaven Sent."

His character spent almost the entire story trapped and alone (aside from the monster set to kill him), and we got to see him at some of his highest and lowest points as he spent four and a half billion years punching his way through a wall with only his fists and an iron determination.
6. Aya Cash as Gretchen Cutler - You're the Worst Season 2 Episode 9, "LCD Soundsystem"

Watching Gretchen invest all of her hope and put all of her emotional distress onto the neighborhood couple that seemed to be perfect was obviously ill-advised. And when that realization came crashing down on her, Cash's performance in the closing scene, as she broke down and began sobbing after realizing that this perfect couple was not so perfect after all, was absolutely astounding.