Season 21

Season twenty-one of Dancing with the Stars premiered on September 14, 2015. Tom Bergeron and Erin Andrews returned as hosts. Carrie Ann Inaba, Julianne Hough, and Bruno Tonioli returned as judges. Len Goodman did not return as a judge this season. The full cast was revealed on September 2.

On November 24, 2015, Bindi Irwin and her partner Derek Hough were crowned champions. Nick Carter and Sharna Burgess finished second, while Alek Skarlatos and Lindsay Arnold placed third. This season set records for the total number of perfect scores awarded (23) and the number of stars to receive at least one perfect score (7). Irwin also set a record with 8 perfect scores and became the second youngest winner of the show at 17 years old (second to Season 8 winner Shawn Johnson, who was 17 at the time of her win). This also marked Hough's sixth competitive win, extending his own record for the most win for a professional dancer on the show.

Couples
The official cast reveal took place on September 2, 2015. Bindi Irwin was the first celebrity to be officially announced as appearing on the season on August 24, 2015. Her celebrity partner however, was not revealed. Victor Espinoza was announced on August 25. Nick Carter was announced on August 26. Hayes Grier, Carlos Pena Jr., and Alexa Vega were announced on August 27. At 15, Hayes Grier is the youngest male to take part in the show. The previous record for males was held by Cody Simpson when he was 17. Also, he is the youngest by birth date by 7 days. Willow Shields was born on June 1, 2000 and Grier was born June 8, 2000. Pena and Vega are the first married couple to compete against each other on the show. Chaka Khan was announced on August 28. Andy Grammer was announced on August 31. Gary Busey was announced on September 1.

Returning professionals that did not compete last season are Karina Smirnoff, Anna Trebunskaya, and Louis van Amstel. Peta Murgatroyd, Artem Chigvintsev, and Kym Johnson were all on last season and did not return. Lindsay Arnold, who was on the troupe for the past 4 seasons makes a return as professional this season.

On September 1, 2015 it was announced that Peta Murgatroyd had dropped out of season 21 due to an ankle injury. Her partner was originally supposed to be Andy Grammer.

This is the first season where two celebrities withdrew during the course of the competition.

Partner Switch Up
During week 5, all celebrities switched up their partners. The new pairs were

Tamar Braxton & Louis van Amstel

Hayes Grier & Allison Holker

Paula Deen & Mark Ballas

Alek Skarlatos & Emma Slater

Bindi Irwin & Valentin Chmerkovskiy

Carlos PenaVega & Lindsay Arnold

Alexa PenaVega & Derek Hough

Andy Grammer & Sharna Burgess

Nick Carter & Witney Carson

Scoring chart

 * This table will only count for scores given by the original judges. Guest judges scores will not be included.

Scoring Chart Key
 * Red numbers indicate the lowest score for each week
 * Green numbers indicate the highest score for each week

Average score chart

 * Based on the traditional 30-point scale.

Highest and lowest scoring performances
The best and worst performances in each dance according to the judges' 30-point scale are as follows:

Couples' highest and lowest scoring dances
According to the traditional 30-point scale. Team dances not included. 

Weekly scores
Unless indicated otherwise, individual judges scores in the charts below (given in parentheses) are listed in this order from left to right: Carrie Ann Inaba, Julianne Hough, Bruno Tonioli.

Week 1
Running order

Week 2: Hometown Glory Week
Running order (Night 1)

Running order (Night 2)

Week 3: TV Night
Individual judges scores in the chart below (given in parentheses) are listed in this order from left to right: Carrie Ann Inaba, Alfonso Ribeiro, Julianne Hough, Bruno Tonioli.

Running order

Week 4: Most Memorable Year
Running order

Week 5: Switch-Up Night
Individual judges scores in the chart below (given in parentheses) are listed in this order from left to right: Carrie Ann Inaba, Julianne Hough, Maksim Chmerkovskiy, Bruno Tonioli. Running order

Week 6: Famous Dances Night
Individual judges scores in the chart below (given in parentheses) are listed in this order from left to right: Carrie Ann Inaba, Julianne Hough, Olivia Newton-John, Bruno Tonioli. Running order

Week 7: Halloween Night
Running order

Week 8: Icons Night
Running order For each dance-off, the couple with the highest remaining score picked the opponent against whom they wanted to dance; the chosen opponent was allowed to pick the dance style (cha-cha-cha, jive or samba). The winner of each dance-off earned two points. The couple who won immunity, Nick and Sharna, received a three-point bonus. For the first time, the general public helped to determine the winner of each dance-off via the show's official website. Running order

Dance chart
The celebrities and professional partners danced one of these routines for each corresponding week:
 * Week 1: Jive, Foxtrot, Cha-Cha-Cha, Salsa, or Quickstep
 * Week 2: Two unlearned dances (Hometown Glory Week)
 * Week 3: One unlearned dance (TV Week)
 * Week 4: One unlearned dance (Most Memorable Year)
 * Week 5: One unlearned dance (Switch-Up Night)
 * Week 6: One unlearned dance (Famous Dances Night)
 * Week 7: One unlearned dance & team freestyle (Halloween Night)
 * Week 8: One unlearned dance & dance-off (Icons Night)
 * Week 9: One unlearned dance & dance duets (Showstoppers Night)
 * Week 10: One unlearned dance & trio dance (Semi-Final)
 * Week 11 Night 1: Judges' Choice & freestyle (Top 4)
 * Week 11 Night 2: 24-Hour Fusion Challenge (Top 3)

Dance Chart Key

Guest judges scores do not factor in to this chart.

Bold indicates encore dance

Guest judges
<p style="margin-top:0.5em;line-height:22.4px;color:rgb(37,37,37);font-family:sans-serif;font-size:14px;">On September 22, it was confirmed that season 19 champion Alfonso Ribeiro would return to the show as a guest judge during Week 3.<sup class="reference" id="cite_ref-auto1_17-1" style="line-height:1;font-size:11.2px;unicode-bidi:-webkit-isolate;">[17]