Mark Bietz

A serious business built on not taking anything too seriously

There is a particular kind of person who can look at a warehouse full of superhero capes, foam lightsabers, and plush Baby Yodas and see a spreadsheet. Mark Bietz is that person, and he means it as a compliment to both the capes and the spreadsheet. As Chief Marketing Officer of FUN.com and its better-known storefront, HalloweenCostumes.com, he spent two decades proving that whimsy and rigor are not opposites. They are, in fact, colleagues.

The company sits in North Mankato, Minnesota, which is not where central casting would place the world's largest online-only costume retailer. There are no rooftop bars, no glass towers, no coastal buzz. What there is, instead, is a family business that grew quietly and enormously by understanding one deceptively simple thing: people love to become someone else, and they will pay for the privilege. Bietz's job was to make sure they became someone else at fun.com rather than anywhere else.

From a college side hustle to the C-suite

Bietz did not arrive at marketing through a corporate training program. He arrived through curiosity and a laptop. While studying at Minnesota State University, Mankato, he started his own internet marketing agency, the kind of scrappy operation where you learn everything because there is no one else to do it. That instinct, learn the whole machine rather than one gear, became the through-line of his career.

He joined the costume company and worked his way up, holding titles that read like a tour of the entire business: VP of Product, VP of Marketing, and eventually, in 2016, Chief Marketing Officer. Along the way he did something most marketers never do. He wandered off his own turf. He dug into web experience, into CRM, into merchandising, and even into operations. He has described those years as a masterclass in curiosity and credited a company culture generous enough to let him poke around in departments that were not technically his problem.

The Halloween problem, and the year-round answer

Every business has a nightmare. For a costume company, the nightmare is the calendar. Halloween is one day. The build-up is a frantic sprint of a few weeks, and then, for the other eleven months, the phones could theoretically go quiet. A lesser marketing operation would simply accept the seasonality, bank the October money, and hibernate.

Bietz refused the hibernation. The strategy he championed treated the costume purchase not as a transaction but as the opening line of a much longer conversation. His team stayed in touch with customers throughout the year, offering tips for throwing a good party, nudges about the costume bought last October, ideas for the next themed occasion. The goal was to make FUN.com feel less like a seasonal vendor and more like a friend who happens to own an unreasonable amount of pop-culture merchandise.

The quiet superpower: personalization

The headline growth numbers, revenue scaled roughly tenfold or more during his tenure, were built on unglamorous machinery. The most effective of it was email personalization. By tailoring merchandising emails to what a customer had bought before and what was currently sitting in their cart, his team produced conversion improvements of 10 to 15 percent over generic blasts. At the scale FUN.com operates, a few percentage points is not a rounding error. It is a new wing on the building.

Then came video. When short-form video swept across the internet, Bietz leaned in rather than watching from the sidelines. FUN.com began producing more video than it ever had, and the results were not just measured in views. Customers started filming themselves in their costumes and sending the clips back, which the brand happily featured across its sites and social channels. It is one thing to run an ad. It is another to build something people want to be in.

The costume-shop philosophy of growth

What makes Bietz interesting is not that he ran a big marketing budget. Plenty of people do that badly. It is that his approach carries an unmistakable point of view, and that point of view is roughly this: curiosity is not a personality quirk, it is a growth strategy. The marketer who understands the warehouse, the CRM, and the customer's living room makes better decisions than the one who understands only the ad account.

That philosophy has since travelled beyond a single company. Bietz has taken on fractional CMO work, lending his scale-up instincts to challenger brands, including a D2C subscription business in the decidedly less glamorous category of cat litter. He advises venture-backed and private-equity-backed brands trying to figure out their digital future. And he has become one of the voices talking early about agentic commerce, the coming world in which AI assistants do a chunk of the shopping on our behalf. He tends to be a step ahead of where commerce is going, which is a useful place for a marketer to stand.

Giving the game back

For someone whose day job is selling the fantasy of being someone else, Bietz has stayed notably grounded in the real place that made him. He serves on the advisory board of Minnesota State University's College of Business, the same institution where he once ran a student marketing agency out of sheer nerve. He also sits on the Google Performance Advertising Council, a seat that puts a Mankato marketer in the room where the tools of the trade get shaped.

It would be easy to make Bietz sound like a man who lucked into a fun industry. The truth is closer to the reverse. He took an industry that most people treat as a once-a-year lark and insisted it could be a serious, data-driven, year-round enterprise, without ever draining the fun out of it. The costumes are still ridiculous. The plush toys are still adorable. The lightsabers still light up. He just made sure the numbers underneath them were every bit as bright.

The lasting lesson of his career is almost suspiciously simple. Take the playful thing seriously, take the serious thing playfully, and never assume the two cannot share an office. In North Mankato, they have shared one for years, and the results speak for themselves.