Making them creepier.

 Retooling some of the common humanoids for an upcoming campaign, I've posted bits and pieces of this over the years:

Gnolls:  virtually invisible beyond 80', they can't see you so good either. You can see each other just fine inside that 80'.

Bugbears: can hide virtually anywhere, if their head fits they can vanish inside or behind an obstacle or object much of the time.  They are the bogyman hiding under the cellar stairs.

Goblins: are magical, not bang-zap magical but they can build doors that connect non-adjacent spaces and can build great halls in spots men and dwarves would have trouble putting a closet. They can see and travel in directions you and I can't normally see.

Kobolds: are furry and beat both live young and lay eggs. The eggs hatch slowly and are an emergency food source. Egg-hatched Kobolds are more likely to have magical abilities.

Orcs: brutal industrial expansionist servants of Levithan, all industry and war are to serve the growth and supremacy of Orc. You can tell when it's orcs because they cut down forests and pollute rivers quicker than humans do. If it's not Orc, it doesn't matter.

Elves: not always the good guys, well not according to people anyway, they usually consider themselves to be the good guys. They can ser and travel in the same directions as goblins can and even more.

Dwarves: not a mono-culture. There are different nations and cultures among dwarves. Contrary to popular belief dwarves are not anti-magical. 

Halflings- have bad guys too.

Hobgoblins: I didn't really change them much, but they do look more like WW-I soldiers in the trenches than they do ersatz-samurai. They live inside hillside bunkers and citadels surrounded by trenches and other battlefield constructions. They are geniuses of military science but not otherwise technologically developed.