There are a bunch of great ideas for zero waste Christmas gift; things like Lunchbots, furoshiki wraps, and experiences are all great options for presents. However, to be frank, money is the best gift of all, especially for us zero wasters. With money, you can buy whatever you want/need, and you don't have to worry about getting/giving something that doesn't look like your brand of pretty, work with your lifestyle, or simply won't be used.
I know giving cash can be a major faux pas, but I'm still going to advocate it, as long as it's given in a certain form. My very favorite version of the money present is for a surprise payment on debt. This takes work (you have to go to the recipients bank and ask about making a payment on their line of credit, auto loan, or mortgage), but I think it gives a huge payoff, as you are relieving an incredible amount of stress on that person's life. I particularly like it, because I'm too irresponsible to dedicate all of my gift money to debt repayment. I put most of it towards that goal, but I always end up making an Ikea trip or stop at the stationary store along the way.
By making a payment on someone's debt, you are lessening their load, furthering their financial goals, and helping them to focus on what really matters to them. If you are worried that your financial gift might go towards furthering a spendy lifestyle, I'd recommend giving them a good book on money management, along with a few loving words of why you care about them and want them to have peace of mind.
My parents were kind enough to offer to pay off my entire credit card balance a while back, but had the stipulation that I disclose all my financial details to them and then close the account. I was young and stubbornly independent (or so I thought), and so refused the deal. It's taken me a long time to get rid of that debt, but doing things the hard way has made the lesson sink permanently in (something which I don't think would have happened otherwise. I may not be as independent as I thought I was, but I really am quite pigheadedly stubborn). Now that I've struggled with my budget and made significantly better choices with money, having someone offer to pay off all my debt would mean the world to me, and would allow me to fully employ all the things I've learned about money since initially using it so badly.
If your gift recipient has been wise or lucky enough to remain debt-free, consider making a contribution to their retirement fund, emergency savings, or giving them a stock or bond. Ensuring a financial future feels priceless, even if it actually has a set dollar amount.
Of course, it's also perfectly fine to just give a body some money, and let them decide what to do with it. Giving a gift, especially of money, means releasing it into the recipient's care; if they spend it on groceries or drugs, that's their choice. They are the ones who have to deal with the consequences, and you are under no obligation to give them more if they blow it.
While there are dozens of zero waste gifts to give and get, I think that getting someone out of debt, padding their future, or just helping them save up for what they want in the now, is a great choice. Yes, zero waste is primarily about treading lightly on the planet; but paying interest rates, extra fees, or penalties for poor foresight can be incredibly wasteful, and drains a person of their focus, energy, and joy, things we could all use more of in our zero waste lives.