The protagonist is your main character, or, if you have an ensemble cast, one of your main characters.
Winnie the Pooh is oftentimes considered the main character by default, which, in all fairness, is an easy assumption to make. We forget that there are plenty of stories where he’s sharing the spotlight though. When this is the case, Piglet, Eeyore, Owl, Rabbit, Kanga, or even her son Roo, are each protagonist in their own right, depending on their level of involvement in that story.
That is to say, the protagonist is the center of attention. Robin may be Batman’s sidekick, but if he’s sharing the page and making just as many decisions to move the story forward as Batman is, then he’s grown from a side character and has become a protagonist.
The Smurfs are another great example of an ensemble cast. There are certainly Smurfs more popular than others (I’m thinking of you Papa Smurf!), but there’s no one Smurf in-particular that steals the spotlight every story. They take turns, and if one story concentrates on one Smurf, then that ONE Smurf is the protagonist of that ONE story.
The protagonist is also said to be the “hero” of your story, though I use the term loosely.
You see, this is another tricky point. Your protagonist doesn’t have to be a hero. They don’t even HAVE to be a good person. They’re merely the character you’ve chosen to focus your story on. Most of the time, it’s also a matter of perspective. Telling a story from the point of view of a monster (or “bad person”) can be fascinating. Maybe they don’t think they’re bad. Maybe they’re actually not. It’s up to the writer to tell their side of the story and shed more light on why they are the way they are.
In Hotel Transylvania, the hit movie by Sony Pictures Animation, there’s a cast full of various monsters, led by Dracula himself. In Monsters, Inc, another hit movie, this time by Pixar Animation Studios, we have Sully, a large beast with blue fur and horns, and Mike Wazowski, his little, green, one-eyed partner. Each are protagonists.
People typically like to root for the protagonist, so having a protagonist that is completely unlikable wouldn’t be a wise idea. You can do it, just be warned, it’s frowned upon. Most the time, when a protagonist comes off as an unlikable character, they have some sort of redeeming quality to make the reader sympathize, understand, or want to root for them. Maybe they’re doing bad things to save their family? Maybe they’re doing bad things because they were raised by bad people and simply don’t know any other way? It’s the writers job to fill in these motivations.
When writing kidlit, we get the remarkable opportunity to make anything we want our protagonist. I’ve read books where unicorns, trees, rocks, and even whole planets are the stars! When all is said and done, just remember that the protagonist is generally the one facing the most obstacles and the primary character propelling your story forward.
Take a character who most would immediately assume was a bad guy, but make him the star of your story. Find key things about him that will make us begin to see things from his point of view.