Walt shared the idea with animator Ub Iwerks, who got to working. Soon, a new cartoon character was born! And Iwerks and Disney had no idea at the time, but this mouse would soon grow into one of the most beloved creations of all time. And his name?

Mortimer Mouse. Yes, that was almost what he was called! Thank goodness that Walt Disney’s wife, Lillian, objected, saying it sounded too formal. Walt changed his name to Mickey, and put him in the short film Steamboat Willie, which they released that year. It was the first ever fully synchronized sound animated short cartoon.

Audiences loved the character. Now, flash forward to 90 years later, and Mickey Mouse is everywhere. He’s the mascot of the Walt Disney Company, one of the most powerful entertainment companies in the world: his likeness appears on T-shirts, watches, caps and almost every kind of merchandise you can think of.

Mickey has appeared in over 130 short films, 10 of them nominated for Academy Awards, and is the first cartoon character to have a star on the Hollywood Walk of Fame. And no one else can rock a pair of red shorts like he does. Not bad for a mouse!

In conjunction with his 90th anniversary today, The Walt Disney Company is going all out, with a host of celebrations worldwide in honor of Mickey Mouse.

How has Mickey Mouse lasted through the years, while other cartoon characters fade into obscurity? According to Dana Jones, The Walt Disney Company Director of Corporate Brand and Financial Management, this was due to Mickey’s ability to keep true to himself.

“Mickey has been able to stay relevant even as times have changed. He grows along with the world. People have nostalgia, they remember him from their childhood, and want to introduce them to their children, or special children in their lives. It keeps the circle going, with people just going back to Mickey because of the joy he brings into their life,” says Jones in a phone interview from Los Angeles.

Mickey’s introduction, Jones said, came at a fortuitous time. It was the end of the 1920s, and things were not looking rosy: the world would suffer the effects of the Great Depression in 1929. To escape from their problems, people would head to movie theaters, where they could laugh at Mickey Mouse cartoons.

Read also: Lost Disney film showing Mickey Mouse's predecessor found in Japan

In many ways, Mickey Mouse was a very layered character. Most of his cartoons tended to show off his positive qualities, such as his charm and kindness. One of his most famous adventures, The Brave Little Tailor, shows his pluck, as Mickey takes on a hostile giant despite only armed with sewing supplies!

Mickey Mouse in Mickey’s Christmas Carol (1983), based on the Charles Dickens’ novel, where he plays the abused, underpaid clerk Bob Crachit.

Mickey, however, was not a perfect character, and that made him interesting. In another famous adventure, The Sorcerer‘s Apprentice (a segment from the film Fantasia), Mickey shows he can be sometimes be a lawbreaker, using his master’s magical hat despite being explicitly warned not to.

Who does Jones think would be a good person to play Mickey if there were a live-action version of him?

“Wow, that’s a good question. I think you would have to be a combination of a couple of people. You’d need someone who brings it all. He goes on adventures and get things done, so you’d need some kind of James Bond type. But he’s also kind and thoughtful, so I’m thinking something like a Tom Hanks, rom-com thing,” says Jones.

Ultimately, however, the biggest appeal of Mickey Mouse probably comes from the fact that he reminds people of their childhood, and the joys associated with those times.

Jones remembers a time, two years ago, during another of Mickey’s birthdays. The Walt Disney Company decided to take Mickey Mouse out of the theme parks, to surprise his fans all around the world. They took Mickey to meet llamas in Peru. And they also took him to visit Kyoto, Japan, where he visited a shop run by an elderly shopkeeper.

“She was a little older. She had probably been a shopkeeper for a while. And when Mickey walked up to her shop, she just started crying. These were tears of joy. And knowing he has that impact on people, is just an amazing thing,” recalls Jones.

“I can’t think of any other character – human or otherwise, who best embodies optimism. Mickey always sees the glass as half full. He always knows things are going to work out. And no matter what time you’re living in, optimism is something you can appreciate. Because optimism brings joy, and Mickey Mouse, he’s great at finding the joy in anything."