How to fill a hole?

[Lazyi]

Any suggestions how I can fill this little hole? TIA!

I would drop a Lego block in it, then fill the rest with wood filler. But I'm a bit of a bodger!

My first thought was a hamster.
Second though is a block of wood.
Is it behind a door?

Yip, Lego and wood filler should do it!

Could you fill the entire space from floor to ceiling with a piece of timber painted to match and square the whole corner off?

I'm assuming no spare floorboard?
How about a small piece of MDF, same width as hole but longer and a screw in the middle.. Put glue on on end, and using screw as a handle feed wood through hole, the glued end comes up under the floorboard and sticks. Then fill on top of the new bit or find a a piece of wood to cut and stick in.
Or perhaps just find a similar bit of wood, cut to shape to fit hole, glue round the edges and see if the glue is enough to hold the wood in place.

Thanks all.... Lego is a good idea. I suspect there is already half a spaceship under the floor boards....

Be aware that this could be hiding a floor issue underneath. We had similar and when the carpet was taken up for replacement, the fitter found the floor underneath had disintegrated. I managed to get a building to knock it all out and refill with concrete.
We apparently have a similar but less severe issue along the internal wall we share with our neighbours so the next time this room is redone, we'll be getting a builder in in plenty of time!

Well, why not make a feature out of it and stick a Lego man in the hole so it looks like he's trying to climb out?

Careful when vacuuming though...

Use expanding foam is it is deep and then finish off with a wood filler?

@WhoWouldHaveThoughtThat

Well, why not make a feature out of it and stick a Lego man in the hole so it looks like he's trying to climb out?

Careful when vacuuming though...

I like that! Could change the figures depending on mood!!!