The problem rarely fits one function.
Growth can stall because the proposition, technology, operating model and leadership have drifted apart. An AI question can expose a process problem. A request for a rebrand can reveal a strategy problem. An acquisition can fail without an operating thesis.
I connect these questions and take responsibility for moving the work across the organisation.
I’m Thiemo Gillissen, a founder, former Managing Partner and now Fractional Chief Growth Officer. For more than 15 years, I have built companies, led multidisciplinary teams and worked across strategy, positioning, design, technology, AI and M&A.
My work has rarely sat neatly inside one function. That is now the point. I step into growth situations where several parts of the business need to move together and no single executive currently owns the whole mandate.
I co-founded Fifteen Seconds in 2012 and helped build the company from an idea into an international platform spanning events, media and learning, growing it to €2m in annual revenue. Its stages hosted speakers from The New York Times, Harvard, Netflix, NASA, National Geographic, Apple, and Walt Disney, while brands including Google, Mercedes-Benz, Microsoft, Red Bull, and IKEA joined as partners.
From 2017 to 2023, I served as Managing Partner at the brand strategy and design firm moodley. I led the digital business and international expansion, built a multidisciplinary team of 40 consultants, designers and engineers, and helped grow annual revenue from €5m to >€10m.
Since then, I have brought this operating experience into focused mandates with founders, owners and leadership teams in growth situations.
Growth is often treated as a marketing problem. In founder-led companies, it is usually a company-wide leadership problem.
The constraint may be strategic focus, founder dependency, lack of capital, an unclear market position, a missing capability, an unrealised AI opportunity or a decision about ownership and exit.
Clients typically bring me in when:
Growth no longer produces an obvious next move.
Important decisions continue to return to the founder.
AI activity is growing faster than measurable AI value.
The market sees less value than the company creates.
A capability must be built, bought or accessed through a partner.
Owners want to exit or become exit-ready.
The next step requires more capital than the business can provide.
I take ownership of the situation, not just one functional piece of it.
I work with founders, owners and CEOs of businesses that have substance: customers or credible market evidence, a capable team and something worth building on.
They usually know that an important change is required, but the situation crosses existing responsibilities. The leadership team may have several interpretations of the problem, while execution is distributed across people who do not share one mandate.
They bring me in because they need someone who can:
Think at company and leadership level.
Challenge assumptions and force clear choices.
Work across commercial, creative and technical questions.
Turn strategic intent into decisions, owners and action.
Stay involved until the work is operating inside the business.
A strong mandate has an engaged founder or CEO, meaningful commercial consequences and an internal team capable of carrying the work forward.
Fractional mandates are typically structured as fixed monthly retainers based on an agreed level of involvement.
We define:
The situation and mandate.
The decisions I am expected to own or facilitate.
The people and functions involved.
The intended business outcomes.
The weekly working cadence.
The conditions for completing or transferring the mandate.
The objective is not to accumulate advisory hours. It is to create clarity, movement and lasting internal ownership.
Based in Lisbon.
Working with founder-led companies across Europe.
I’m Thiemo Gillissen, a Fractional Chief Growth Officer with more than 15 years of experience building companies and leading growth across strategy, positioning, technology, AI and M&A. Bring me the growth question that keeps returning to the leadership table.