Whatever your norm is that's appropriate for the weather. Shirt, shoes, socks, tights, hat, arm warmers gloves. Be prepared for the elements. Think about what it's likely to be like during your night run.
You never know when you are going to have to fill in for another.
Whatever you use to roll out those stiff muscles bring 'em! Better to have a magic stick than a pillow if you are tight on space.
At least one pair, consider bringing two.
Flip-flops are great, or whatever else you are comfortable just wearing around when you aren't running.
There are several products on the market, Glide is the most popular. Even if you don't normally use it bring some. Apply before you need it because once you need it, it's too late.
You are going to stink! Whenever possible remove the stink whether it's jumping in a lake or stream or taking a shower in a high school locker room. The towel can also double as a pillow in a pinch or if you are packing lite.