2025 Honorees

Sian Rigby Manville

Head of Growth

“As a marketer, you have to be willing to take big bets.”

Marketer2025

Tell us about your company and role.

As Head of Growth at Kosas Cosmetics, I lead our growth marketing initiatives across all digital channels. Kosas is a clean beauty brand disrupting the industry with formulas that double as both makeup and clinically tested skincare. In my role, I oversee our performance marketing strategy and branded media, with a particular focus on paid social, influencer/creator partnerships, and eCommerce growth.

 

How would you describe yourself?

I’m scrappy and focused, but always trying to bring lightness and optimism to work. This balance is reflected in my role as a data-driven creative + media strategist who thrives at the intersection of analytics and visual storytelling. I’m passionate about making creative speak to us in data, and vice versa, always looking for the magic in between the left- and right- brain that will drive business growth. I’m also an advocate for diversity and inclusion in beauty and eCommerce, always looking for ways to create more equitable spaces in our industry.

What qualities does an effective marketer need to have?

Creativity, curiosity, and adaptability are the most obvious answers, but more than these, courage is most important to me. Once a business grows to a certain size, small bets don’t stack like they used to. Bold swings and clear points of view make a brand stand out and resonate with a consumer. You have to be willing to take big bets, drive consensus and understanding around the risk calculus, and adapt to maximize wins and learn from losses. When the culture is right, it can feel like a high-stakes poker game with a team-sports mentality. I love working with people who have a love for the game, as I do myself.

What has been your biggest professional success so far?

One of my proudest achievements has been pioneering Kosas’ TikTok paid program during the platform’s early days, helping establish a powerful sales-generating flywheel that combines paid marketing, organic content, and influencer partnerships. Before that, at Ampush, I played a key role in scaling DTC brands like Glossier and Hubble Contacts during the earlier days of Meta advertising. I’m equally proud of my work in diversity and inclusion at Ampush, where I led a project to analyze and address gender disparities in recruitment, ultimately helping the company reach its goals in workplace diversity.

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What causes are you most passionate about?

I am passionate about diversity and equality broadly, and also specifically in the beauty industry, where people of color and queer people are a large part of both the influencer and customer base, but often underserved. I believe the beauty industry is one where a brand’s values are transparently obvious to the consumer through product and shade development. It is antithetical to the mission of a brand if they stay silent on issues that impact their community, and don’t elevate diverse voices in their content and marketing platforms. I try to serve these communities daily in whatever way I can, although it will always be a work in progress. 

What do you think is the biggest challenge facing eCommerce brands?

Cutting through the noise while maintaining authenticity and efficiency in marketing spend.

What's your favorite loyalty program or subscription offering from an eCommerce brand?

I absolutely love early access to a sale or launch as a returning customer, and see this work well at Kosas too. Some recent brands I’ve shopped “early” are Briogeo, Dieux Skin, Lunya (they do this so well!), and of course, Sephora as a loyal Rouge customer. For subscription, I have been subscribed to Cometeer Coffee for over three years now and their UX for managing shipments is by far the easiest I’ve ever used.

 

What do you geek out over?

I follow clean beauty brands like other people follow sports teams. I could also talk about CPMs for hours. On the personal side, I’m consumed by hot yoga, Chopin, fantasy books and my dog, Scout.