I always find the job title "secretary" fascinating. It's both an administrative support person, almost always non-exempt, and not responsible for high-level activities, and an exceedingly high government official, with incredibly complex and varied responsibilities, some of whom are responsible for literally hundreds of thousands of employees.
The first definition of secretary has fallen out of fashion and been replaced with the "administrative assistant" role, but if we say, "Mary is a secretary," it's doubtful your next question will be, "Which cabinet post does she hold?"
In small to medium businesses, titles can be just as confusing because people often do numerous different things. When I worked for a company with more than 30,000 employees, I was one of 300 or so HR people, so my title could very accurately reflect the actual job I did. But, if you're one of 20 people in an office, your responsibilities can be completely varied. You could be a trained accountant that also handles payroll, new employee onboarding, and helps out with the marketing. You could be the operations director who works with your manufacturer in China, and creates marketing plans and is responsible for keeping the bathroom stocked with toilet paper. (The last part, which an extremely important responsibility, can probably be left off your resume.)
So, when you're trying to come up with job titles "Jack of All Trades" isn't the best solution for your business card or LinkedIn Profile. Here are some ideas to help you pick job titles for your staff or help you advocate for the title you want.
What do customers, clients, and vendors think you do?
If you are client or vendor facing, your title should reflect that aspect of the position. A vendor will take a Marketing Manager's opinion on ad campaigns more seriously than an HR Manager who, for some unknown reason, is meeting with the design firms. It doesn't matter that you do both.
On the flip side, if the only outside people you speak with are job candidates, having an HR title makes more sense than another one. You don't want to bring confusion into the picture when the Finance Director is asking candidates to fill out applications for a job in marketing.
A caution, of course. In lots of situations, you'll meet with external people in more than one capacity. Then you will have to pick something or have a double title: "Jane Doe, Marketing and HR, ACME LLC."
What is your true level of experience?
While you may think that all companies should be strictly hierarchical with all the direct reports to the owner being Vice Presidents, that doesn't make a lot of sense if these people aren't seasoned professionals. In a small or medium sized business, you won't have layers of VPs, directors, managers, and individual contributors. You'll have one or two people in every function.
Therefore, your title should reflect not only your responsibilities but your level of experience. This means that, while you may be the top person in an area, you may be better off with a manager title rather than a VP title.
While clients like talking to the top person, if you don't have the expertise level to pull off a director title, you'll look like a fool. Additionally, think about where you would go if you left this position for one in a bigger company. Would you jump in on a senior team or would you be in middle management?
How would you post this position on Indeed?
Or any other job board--or even your own web page jobs section, how would you label this position if you needed to hire someone? The primary responsibilities would drive the title. The current person should have that same title.
Stay away from the cheesy or trendy or hip titles
You know what these are. They are awful. They are bad ideas. I will mock you for them.
Don't become the job title police
Business cards aren't as popular as they once were, but email signatures and LinkedIn profiles are popular. And both contain titles. Other than monitoring level titles (Director, VP, Senior, etc), let people have the flexibility to explain what it is they actually do. Give a bit of latitude for people who want to pick their own title. Yes, the boss gets the final say, but take their opinion into consideration.
Job titles can be tricky because they not only matter right now, they matter for the employee's future. Make sure your systems and records reflect all the areas of responsibility your former employees had so that if someone calls for a reference you don't say, "Nope, Jane was our marketing manager, not the HR manager," even though she did both jobs. People move on, and it's in your best interest, as a company, to have former employees that think fondly of you.