In general: whenever we see Cecil go against the City Council and/or authority and challenge the status quo. This is a man who'd wanted to be a radio host all his life, which in Night Vale basically requires you to become the Mouth of Sauron and never toe the line. Watching someone like him show the backbone to go against the foundation of his job and life is truly inspiring. Compare Cecil early in the series to Episode 108 - where he audibly begs Night Vale not to follow the Mayor's example.
Cecil, throughout the entire series, reports through everything, no matter how bad it gets.
From Episode 28, Tamika Flynn leading her fellow imprisoned children to freedom from the summer reading program. It's unclear how she accomplished this, but it involved beheading a librarian and completing a book above her reading level. Not just any book either- it was Cry, the Beloved Country, a book on the 10th grade Honors English curriculum. Tamika was only 12 at this time.
Surviving any amount of time as one of the interns at the Radio Station is an incredible accomplishments in of itself considering how often they seem to die. However, Dana or Dana's double deserves a special mention considering she's the longest surviving one to date.
During "The Sandstorm", either Dana or her double manages to off her counterpart with nothing more than a broken stapler.
On Cecil's orders Dana or her double enters the forbidden Dog Park, while the gates are temporarily opened. She sends back a cell phone picture of what's inside, but becomes trapped along with several other citizens when the gates slam closed again. After her texts stop and his iPhone starts bleeding when he tries to text her back, Cecil assumes her to be dead.
Dana steps up in a way that surprises both Cecil and the audience when, several episodes later, he gets another text from Dana, telling him that's she's very much alive and even still trying to do her job by giving him what information she's gathered about the nature of the Dog Park and The Man in the Tan Jacket, who she's befriended. While she's suffering from hunger, she's still determined to see this through.
Episode 30, entitled "Dana", is entirely devoted to her being awesome. She survives for several weeks on food thrown over the fence by concerned listeners, explores and then escapes the Dog Park, finds herself in the house that doesn't exist from the pilot, and is now venturing through the desert on a different plane of reality, still determined to learn and report what she can. GO DANA!
Later, Dana stumbles upon a vast masked army of giants and they are so moved by her strength and wisdom that they make her their leader.
As of Episode 49, Dana is the new Mayor of Night Vale as chosen by the pulses in Hidden Gorge
As of episode 35, Tamika Flynn is training a militia composed entirely of children and, when questioned about it, issues a direct threat to StrexCorp. The beginning of the first full-fledged resistance against the Strex takeover, headed by a 12-year-old.
When a reporter asks her followup questions, she challenges him to "a hundred days of single combat," at which point he makes a hasty exit, pursued by a mob of soldier children.
Episode 36, "Missing". StrexCorp hunts after Tamika Flynn, and tries to shut down Cecil's show. In the meantime, both Tamika and Cecil incite Night Vale to revolution, Tamika through her direct and inspiring influence, Cecil with his words and his voice. Cecil's crowning moment is either the episode's "traffic" report, or managing to tap into the broadcast after having his mic cut and escaping the studio, hiding on the roof and continuing to urge the people of Night Vale to fight StrexCorp.
"If station management is listening, I, of course, hope we find Tamika Flynn and bring her home safely. I hope that she will find you first, that is."
Episode 38 Cecil hitting John Peters - you know, the impostor - upside the head with his mobile phone and knocking him out.
Episode 42 Cecil mentioning how the doors to the radio station are made of reclaimed bloodstone and cannot be removed, casually adding "Our new owners have had to learn to live with those doors, bleeding on their way out. Good practice for them."
The entirety of episode 46, with Cecil communicating via Morse code that everyone in Night Vale participate in Tamika's revolution, and as the episode goes on. The weather's title, "Take Up Your Spade," only cements this further. He taunts StrexCorp station management as it goes on. He even outright calls StrexCorp terrible after the weather when the revolution failsand Tamika is captured.
The way the background music suddenly picks up the pace just as Tamika and her army appear over StrexCorp piloting a fleet of commandeered helicopters, while Cecil simultaneously reveals that he has locked his producer in his booth and has taken over control of the station, adds just the right touch to make that particular moment truly awesome.
Cecil: I am telling this now to my producer Daniel, who is throwing chairs in the control room. I am telling this now to my producer Daniel, who I have locked in the control room. I am showing my producer Daniel that I am running the show from my own mixer, as he stares dumbly at the cables he just yanked from the walls.
In episode 47, Company Picnic, we learn that Carlos managed to escape from StrexCorp when nobody else could. Perfect uncaptured Carlos.
Tamika: Lady, I've trained for months. I've taken down your helicopters with only a slingshot. I've looked at a librarian right in the area where most creatures would have eyes. You. Do not. Scare me.
Leann Hart and her hatchet tearing a bloody swath through StrexCorp office workers during Episode 49, shouting "I AM IMAGINING YOU ALL AS NEWS BLOGGERS! YOU ARE DESTROYING YEARS OF JOURNALISTIC TRADITION!"
Cecil's entrance in Part A:
Cecil: [as the music starts to build ] Think back. Look forward. Listen timelessly. Welcome to Night Vale! [theme plays]
Another moment goes to Sarah Sultan, who, despite being a smooth, fist sized river rock, still manages to throw (or have herself thrown) into the fray in order to help save what was definitely not an angel (formerly known as Marcus Vanston).
Steve Carlsberg, of all people, gets one in 49-B, when Kevin pushes his Berserk Button (Janice may be handicapped, but she is not 'broken'), he literally picks Kevin up and throws him through one of the open 'oak doors'. Ends up one of the few times that Cecil is nearly stunned into speechlessness.
Steve: Now you listen to me! (picks up Kevin by the lapels) You will not change my hometown! You will not change my stepbrother! And, Kevin of Desert Bluffs, you will not change... or fix... or do anything at all to my little girl!
Cross-posted from CMOF: Cecil weaponizing the Weather in "The University of What It Is", allowing the staff of the titular college to escape an angry mob by forcing said mob to stand around awkwardly for several minutes listening to music.
Similarly, after years of brainwashing and blind obedience, Cecil asks his neighbors to try showing empathy and understanding towards strangers. When he realizes that they can't, he finally sees that his friends and companions are "a dangerous combination of repression and indoctrination". Hearing him finally comprehend what was clearly wrong with the town's behavior for the past 54 episodes is surreal, and a pretty impressive feat for someone who's as brainwashed as anyone else in Night Vale. Not at all lessened by the immediate contrast with his actions in the last episode (fighting the temptation to welcome an innocent carnival in town because it instinctively feels wrong) or the fact that each time, his impulse to be welcoming is somehow due to the Power of Love.
Tamika Flynn managing to open a book club in "worms..." despite the City Council's hatred of literature. She even steals a book from the forbidden knowledge section of the library.
Doubles as a Tear Jerker, but Cecil's decision to abandon Night Vale for the desert otherworld is really the first time he has ever taken true initiative in his own life that flies in the face of both his strict Night Vale upbringing and his preordained role as the Voice of Night Vale. He's come a long way from the usual sycophantic, toe-the-line type he was when we first met him.
Also a Tear Jerker, but Violet finally taking matters into his own claws to fight back against the 4/5 of his body that has been dragging him around for so long trying to get revenge is extremely brave for such a usually neurotic and nervous dragon. Even the establishment of Night Vale commends him for this, and while the other 4/5 of his body rots in a jail cell, he has a hole in the wall that he can poke himself out of to talk with the town and enjoy (a given measure for 1/5 of a five-headed dragon) freedom from his bodymates.
Janice's incredibly clever plan to pull off a heist against the City Council in episode 71.
Episode 74 has people stand up against City Council's regulations on the Dog Park. And they actually get something out of it!
Episode 80 has Intern Kumar refuse to deny the existence of Angels after they rescue him from the Strangers.
Episode 83 gives us more Mayor Dana action. This time she solves Desert Bluffs' financial crisis by merging the town with Night Vale. When Sheriff Sam and City Council inevitably try to put a stop to this, Mayor Dana stops them with a Rousing Speech, mixed with You Are Better Than You Think You Are. It's also made clear the pressures of being mayor are taking their toll on Dana, but that doesn't stop her.