What to do with dark paneling

You could cover it with bead board, white wash or grey wash it, wallpaper it, cover it with 3d faux stone panels...

You can paint it, wallpaper it or cover it with bead board. Personally, I like the idea putting a chair rail on it and using one finish above the chair rail and a different finish below the chair rail.

Paint it or white wash it

Or you can stain it to a lighter color/Whitewash

I have wallpapered paneling successfully. It was a dark angling in a finished basement.

There are so many things that can be done. All of the suggestions are good depending on your style and what is in your room. One thing that wasn't suggested but is very popular these days is shiplap. If you have pictures of the room, it's easier to make suggestions.

You can paint it. If you want to fill the lines then I would use a wood filler, sand it off smooth, prime with Zinsser Bullseye 1-2-3 Primer and then put your finish coat on. If you tint your primer with the same color as your paint it will make for easier cover up and a much nicer job.

First, paint the wall with a primer. Then paint with a color that either matches or contrasts with the other walls, based on your preference. I would use a textured paint to blend the "hardscape" (fireplace) wall with the "softscape" (drywall) wall. The textured wall paint (available at Lowes) will give the room a designed-like/rich finish that looks intentional. I recommend the "Sandstone" textured paint made by Valspar.

You can lightly sand it, brush off dust and paint it any color you want.

Paint it! It really changes the look of a room. And! It doesn't have to be white/off white. Colors look great in this application. Depending on you decor, it coukd look country or modern. Add some cove molding if your budget allows and it will really shine!

Paint or wallpaper. If there are grooves in the paneling fill them, them prime for wallpaper and hang!

We painted, but weren't really happy with the look. The we bought wallpaper that had a shiny surface.. wrong!! it showed every groove. Then we went with a textured wallpaper and were very happy with the results. Just avoid anything shiny.

Thank you all so much for your suggestions. Bead board and wall paper it is.