Things I Always Pack
I believe there are few things that are necessary to bring that your average traveller may not bring. Some of these items may apply to certain countries only but typically here is my list of must packs:

1. A washcloth
Not all countries will provide you with a washcloth in hotel rooms. Most provide towels (with exceptions of hostels).

2. Mini Toiletries 
When I travel, I rarely bring a checked bag. This means I have to bring my toiletries under 100ML. I always make sure I have shampoo, conditioner, body wash, sunscreen, bug spray, aloe, facewhipes, Q-tips, and kleenex. You can get "travel" versions of these in stores like Dollarama & Wal-mart. You can also order online empty 100ml bottles that you can fill with your own products. 

3. Toilet Paper/Tissues
This may sound silly, but there have been more times then one that I have needed my own toilet paper. Countries in Asia and Caribbean don't always supply them in their bathrooms

4. Hand Sanitizer
To go along with my previous post, you may never know what kind of situations you may find yourself in. Countries in Asia don't have an actual toilet bowl and public "holes" can be very disgusting. None-the-less you should always be sanitizing to make sure you don't get sick on vacation

5. Granola Bars/Mr.Noodles
I don't consider myself an extremely picky eater, but I definitely have my limitations. I always like to have Mr.Noodles as a back up incase I can't find something in the area I like. Most hotels provide a kettle. Granola Bars are perfect for tours as some can be 8 hours long without frequent stops. Sometimes I will come home with only 1 bar and sometimes the whole package but it's much better to be safe rather then sorry.

6. Sarong 
Again, not all countries may require this but its not only good for temples! It's a great light cover up for when you don't want to walk around in a bathing suit. It can also double as a towel/blanket. They're pretty amazing as you can wear them as a skirt or dress or even a scarf or head wear. 

7. Re-Useable Utensils/Straw
Don't try to get away with the real ones - they'll take them at the airport. But having utensils and your own straw not only can help with the environment but you never know when you'll need them!

8. Flip Flops
Showers can be gross.... enough said

9. A fanny pack/wallet belt
Pitpocketing is a serious issue in lots of countries. Its never a bad idea to have something that can go under your clothes or is very tight to your body to hold your belongings

10. Medical Supplies
Tums, Pepto, Advil, Bandaids. You literally never know. 

11. Plastic Bag
Perfect for wet or dirty clothes

12. Drawstring Bag
Its a lot easier to carry around then a large backpack. Bring one that is waterproof or resistant and full closes. You can use it anywhere and is the perfect size. 

13. Insulated water bottle
Having your own water bottle saves you from always having to buy one and if its insulated it'll help it stay cold much longer. 

14. Hotel Alarm Wedge
I purchased this from amazon and bring it whenever I do solo travel, it doesn't matter how fancy/safe the hotel seems, I always use it. It goes under the door so if someone tries to get in, the alarm will sound alerting me and others. I will bring this even if I am travelling with someone if I feel the country may be less safe than others.