- "It is heartening to see so many of you here, even in weather like this. But a lack of heart and school spirit has never been the Riverdale way. Tonight's pep rally isn't like any other we've had in the past. And we shouldn't pretend that it is. Which is why I would like to dedicate this evening to the memory of one of our brightest. Jason Blossom. We're with him tonight. "
- —Mayor McCoy to the crowd[src]
McCoy is not only the powerful and fabulous Mayor of Riverdale, but also the mother of soon-to-be-world-famous Josie, of Josie & The Pussycats fame. Chic and driven, Mayor McCoy is struggling to guide Riverdale through the crisis precipitated by the mysterious death of Jason Blossom, all while making sure the town’s upcoming 75th Jubilee Celebration goes off without a hitch.
Sierra McCoy grew up in the small and close minded town of Riverdale. She attended Riverdale High School, and later proceeded to raise a family with Myles McCoy. The two of them have a daughter together, named Josie. Some time after this, Sierra became Mayor of Riverdale, and while some people are opening up, everyone in town was not so welcoming of a mayor of color.
Throughout the SeriesEdit
Before the Pep Rally kicked off, Mayor McCoy joined Mr. Weatherbee and Coach Clayton on stage to personally thank everyone in attendance. She is gladden by the turn out, a lack of heart and school spirit has never been the way of Riverdale High School, even in spite of the weather and mysterious death of Jason Blossom. She reminded the crowd that the pep-rally is like no other they've had before, which is why she dedicated the evening to the memory Jason Blossom. She then welcomed the River Vixens and Josie and the Pussycats to the stage to perform. 
Mayor McCoy welcomed everyone to the first annual Taste of Riverdale. She went on the say that the event taking place, proved that Riverdale is a town that when tragedy strikes, they pick themselves back up. After her speech, Sierra approached Cliff and Penelope Blossom, just to check in on how they're dealing with Jason's death, but she found herself on the end of a snarky reply from Penelope instead. 
Mayor McCoy apologized to Jughead as there was nothing she could do in stopping the demolition of the Twilight Drive-In. Good riddance, it's a cesspool filled with criminals. With Andrews Construction sanctioned to demolish the lot on Monday, the deal is done. When Jughead was younger, his family would always go to the drive-in, he and his sister, Jeallybean would hide in the trunk as they couldn't always afford tickets, the drive-in is like his home. While, she appreciated the sentiment that he holds towards the drive-in, the future of Riverdale is at stake. Mayor McCoy later received a secret donation from Hermione Lodge towards her re-election campaign, in exchange, Lodge Industries would receive the twilight drive-in, which is one of the most prime pieces of real-estate in Riverdale. She made a point to remind Hermione that no one could know of their deal, especially not the Blossoms. 
Upon learning that Valerie had quit the Pussycats, Sierra believed the best solution was to replace her, as everyone is replaceable with the exception of Josie. With Myles McCoy, Josie's father attending their performance at the Variety Show, she would hate for Josie to let him down, especially since he had to cancel two concerts. She insisted that Josie find a new member, someone skinny, beautiful, and of color. She was then invited over for diner by Fred Andrews and Hermione Lodge, in an attempt for them to plead his case for the construction contract of the land that once housed the Twilight Drive-In. The topic of discussion changed several times throughout the night before ending with Fred's bid, one that Sierra was more than willing to grant him, as she described Fred as a working man who lived in the real world and found his bid refreshing. However, the buyer was already in the process of accepting another bid and it would take two share-holder signatures to stop the process and the chances of that happening were fairly unlikely.
The night of the Variety Show had finally come, Sierra and Myles sat in the audience as Josie and the Pussycats performed on stage, Sierra thoroughly enjoyed her daughter's performance, Myles on the other hand was left unimpressed, as he exited the event halfway through the performance. After the show, she found Josie in tears, so Sierra hugged her tight. 
Mayor McCoy and Mr. Weatherbee approached Betty Cooper during the Homecoming dance, hoping to review the evening's itinerary. She requested that Betty escort her up to the stage, however, Betty was fairly preoccupied, handing the duty off to principal Weatherbee. She then welcomed Archie Andrews and Veronica Lodge to the stage for their performance. Afterwards, she was notified by Sheriff Keller that FP Jones was arrested for the murder of Jason Blossom.
Mayor McCoy and Sheriff Keller were interrupted by Alice Cooper, who entered her office at the Town Hall, baring a USB drive, which contained surveillance video of Jason Blossom's murder. Upon watching the video, they discovered that FP Jones was not the killer, despite his initial confession. Jason was killed by his own father, Clifford Blossom, in the basement of the Whyte Wyrm.
The murder of Jason Blossom had revealed several dark truths, none of which Mayor McCoy was eager to face, as she screamed at Sheriff Keller to destroy every last trace of corruption. In the days leading up to the 75th Anniversary Jubilee, Mayor McCoy approached Archie Andrews and Betty Cooper with an offer to feature them both at the event, in their honor since the two of them helped bring peace and justice back to the streets of Riverdale. She informed Archie that the Pussycats would be performing at the Jubilee, so she would love it if he could join them. As for Betty, Mayor McCoy simply wanted her to speak at the event, she thought it best if the townspeople of Riverdale heard from their best and brightest. Archie inquired about Jughead, who also played a large role in solving the mystery of Jason death.
While she was fond of him, and he was more than welcome to attend the Jubilee, the Mayor thought it would be confusing to have him up on stage while his father was locked up at the same time for his involvement in Jason's death. She reminded Archie and Betty that they were the heroes that the town desperately needed. The night of the Jubilee had finally arrived, as Mayor McCoy welcomed all to the Town Hall in celebration of the town's 75th anniversary. She couldn't have been anymore thrilled to introduce her daughter, Josie, and her Pussycats, along side Archie. Much to her surprise, Josie and Archie would not be playing the song she had previously signed off on, instead they played one of his sings.
Initially upset and confused, she came around to enjoy the song as the crowd applauded their performance. Unfortunately, the Jubilee went a bit off the rails as Betty gave her speech in front of the entire town, accusing them all of writing off FP Jones because everyone was so quick to place the blame on him. Betty went on to explain that the town was at a crossroads, and that each of them needed to do better or else what happened to Jason wouldn't be the last. From backstage, Mayor McCoy didn't look to pleased, in fact she looked discouraged, perhaps at her own behavior.
Sierra is a beautiful middle-age woman with a slim figure. She has dark skin, brown hair and deep brown eyes. She often wears a lot of make up; lipstick, eye shadow, etc. As for her clothing choices, Sierra typically has on long, dark colored dresses.
- "Chapter Two: A Touch of Evil"
- "Chapter Three: Body Double"
- "Chapter Four: The Last Picture Show"
- "Chapter Six: Faster, Pussycats! Kill! Kill!"
- "Chapter Eleven: To Riverdale and Back Again"
- "Chapter Twelve: Anatomy of a Murder"
- "Chapter Thirteen: The Sweet Hereafter"
- See also: Category:Images of Sierra McCoy