Proudest Mentor Moment
"Met Ariel Harmoko for coffee after he cold-added me on LinkedIn. I liked that his profile said he was a go-kart champion and worked in ML before AI was cool. Meeting him, I had a hunch that there was something about him and what he was building. I decided to invest via my syndicate and arranged for him to meet the folks at Andreessen Horowitz at a dinner I was hosting. I helped him show his best side to the VCs over the following weeks, while working the other side to ensure the relationship was fruitful. a16z eventually decided to invest in his company, which has propelled his growth forward."
About
Guillaume Roux-Romestaing advises startups on go-to-market work, operates 181 Angels and serves as an a16z venture scout.
Co-founder and operator, 181 Angels
Guillaume Roux-Romestaing is a startup go-to-market adviser, angel investor and co-founder of the 181 Angels syndicate. He is also an a16z venture scout, focused on discovering early-stage startups. His work includes connecting European startup experience with San Francisco’s operating and investor networks.
Previously, Roux-Romestaing worked in sales and partnerships at 11x and in growth for Wordware’s Sauna product. His background also includes venture building at Founders Forum. He is building Samaritan, a prayer and scripture-reflection app. Across these activities, his experience centers on early-stage distribution, founder-led sales, investor networks and entering the US market.
Experience Guillaume brings to founders
- Go-to-market strategy
- Founder-led sales
- US market entry
- Angel investing
Operating and investing experience
A selection of companies and roles connected to Guillaume Roux-Romestaing.
Ventures
181 Angels
Co-founder and operator
Andreessen Horowitz
Venture scout
Samaritan
Builder
11x
Former sales and partnerships operator
Highlights
- Identified as an a16z venture scout in 2025.
- Co-founded the 181 Angels investment syndicate.
- Worked in growth, sales and partnerships at AI startups.
Questionsfounders ask aboutGuillaume Roux-Romestaing
Who is Guillaume Roux-Romestaing?
Guillaume Roux-Romestaing advises startups on go-to-market work, operates 181 Angels and serves as an a16z venture scout.
What experience does Guillaume Roux-Romestaing bring to mentoring?
Their experience spans go-to-market strategy, founder-led sales, US market entry and angel investing.
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