Stephen O'Brien
Investor & Head of Platform at MANTIS Venture Capital
Los Angeles, California
Stephen O'Brien, Investor & Head of Platform at MANTIS Venture Capital is an active investor based in Los Angeles, California. This profile covers what Stephen O'Brien backs, at which stage, and how founders can reach out in 2026.
Stephen O'Brien is an investor and Head of Platform at Mantis Venture Capital, passionate about startups, ESG, clean tech, and innovation.
Stephen O'Brien invests in Climate & Energy, typically at Seed and Series A.
- Location
- Los Angeles, California
- Typical check
- $625K
What does Stephen O'Brien invest in?
- Investor type
- VC
- Invests in
- Climate & Energy
Where is Stephen O'Brien based?
Stephen O'Brien is based in Los Angeles, California.
- Browse more startup investors near Stephen O'Brien:
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How to reach Stephen O'Brien
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About this profile
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Cite this page
Round Funded. "Stephen O'Brien." Round Funded investor database, updated September 22, 2026.
Stable URL, it will not change: https://www.roundfunded.com/en/investor/stephen-o-brien
Frequently Asked Questions
Who is Stephen O'Brien?
Stephen O'Brien, Investor & Head of Platform at MANTIS Venture Capital is an active investor based in Los Angeles, California. Stephen O'Brien invests in Climate & Energy, typically at Seed and Series A.
What does Stephen O'Brien invest in?
Stephen O'Brien invests in Climate & Energy, typically at Seed and Series A. Match your sector and stage, then reach out with a personalized pitch.
What stage does Stephen O'Brien invest at?
Stephen O'Brien typically invests at Seed and Series A. Lead with traction that fits the stage when you reach out.
What is Stephen O'Brien's typical check size?
Stephen O'Brien typically writes checks around $625K. Use it as a signal for whether your raise fits their stage.
Where is Stephen O'Brien based?
Stephen O'Brien is based in Los Angeles, California.
How do founders reach investors like this?
Round Funded lists active investors with verified, professional contact details for signed-up founders. Filter by sector, stage and location, then send a personalized pitch from your own inbox.
What is Round Funded?
Round Funded is an investor database and outreach platform for startup founders. It lists 60,000+ active investors with verified contacts, filtered to recent investment activity, and lets founders send personalized pitches from their own Gmail, track replies, and share a free Data Room. Round+ starts at $99 per month with a 3-day trial.
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