Yes! I have my closest "imaginary" friend, who I'll call C, and by effect the little group I've created for us. It's a mix of a sort of modern land combined with an escape to a fantasy world.
Genuinely, C had saved my life.
I made her when I was 8, and our teacher read us all a book at school. It wasn't anything special, just about a mischievous little girl who always aimed to have fun, even if it got her into trouble. I always really wanted to be carefree in the way other kids my age were, and then I saw this girl, who had a bundle of curly hair and a lovely name and I thought "what if she looked a bit more like me?"
And then C came to be! She's my closest friend and confidant. When I was younger, I think I overly relied on her, to the point I'd tap out of conversations in the real world and zone out so I could be with her and all our friends.
But to be fair, I was so incredibly stressed it felt like the only way to go by. Now, I've gotten better at coping(?) Or maybe worse. So we don't hang out as much, but she's grown up with me and is still always there anyway, just at the back of my brain.
It's thanks to her I've become I'm more confident. Whenever I'm scared or nervous, I try to emulate how she would be, in all her brazen attitude and confidence. She's everything I could want to be.
Sometimes there are other characters from tv shows I'm currently watching that will pop up to visit, but C and the others are the ogs and my one true happy place.