Alley's departure was announced mid-way through the hour-long show. The actress smiled when her name was announced.
She said it had been an honor to have been asked to compete a second time on the show.
"I learned more about dancing, believe it or not," she said, and thanked and her professional dance partner Maksim Chmerkovskiy. "He's so patient with me and he's so helpful to me and I just love dancing…"
She also thanked her fans and the show's three judges for their feedback.
Marini, the actor who was in the middle of a close pack last night, was fiercely competitive throughout the season and was a consistent high scorer. He failed to capture a perfect score of 30 but did come within a half point of his goal.
He learned was going home at the end of the show, and called his second turn on the competition "an incredible experience."
"I tried my very best," he said, adding that Peta Murgatroyd, his professional dance partner, was "an angel out there, teaching me amazing things."
He also thanked his wife for her support and acknowledged that his participation on the show had been a challenge for his family.
Generally one star is sent home each Tuesday on the results show but because there was no show - and therefore no elimination - on Election Day, two stars were voted off tonight.
Elimination is based on a combination of judges' scores plus audience votes. Alley and Marini had the two lowest overall scores after two weeks of audience votes and judges' scores were combined.
Tonight' show featured live performances from Kylie Minogue, Ne-Yo and the cast of the Broadway musical "Newsies."
Returning next week to perform in the semi-finals are Olympian Apolo Ohno, actress Kelly Monaco, NFL legend Emmitt Smith, Olympian Shawn Johnson and TV personality Melissa Rycroft.
They will be dancing to styles and themes that they picked for each other tonight. Their choices were: Surfer Flamenco, Knight Rider Bhangra, Big Top Jazz, Mad Monk Merengue, Espionage Lindy Hop and Caveman Hustle.