Holly Ventures Research
Overview
Holly Ventures is a $33 million solo-GP seed fund that invests exclusively in cybersecurity startups from "Day Zero" — the earliest possible stage of company building, including ideation. Founded by John Brennan in 2025 and headquartered in San Francisco, the firm is intentionally designed as a counter-model to the large, multi-stage cyber platforms that have come to dominate the space. Holly Ventures Fund I closed in December 2025 and is actively deploying capital.
Investment Thesis
Holly Ventures' thesis is simple and tightly scoped: the world's best cybersecurity founders deserve a dedicated seed-stage partner focused entirely on their success, starting before anyone else is involved. The firm's tagline — "Backing the world's best cybersecurity founders from day zero" — captures the philosophy. Brennan argues that early-stage security founders generally aren't lacking for capital; what they lack is hands-on engagement from someone with deep sector expertise and a network that opens real doors.
The firm is explicitly built for "access, not just capital." By writing smaller, collaborative checks alongside larger lead investors, Holly Ventures preserves optionality on founders' cap tables while delivering a network and operating support typically associated with a much larger fund. The LPs themselves are a strategic asset: they include institutional investors from Bessemer Venture Partners, Ballistic Ventures, CRV, Wing VC, IVP, TCV, Notable Capital, Team8, Brightmind, Ten Eleven Ventures, Vanderbilt University, and Okta Ventures. This LP base creates a high-density network of enterprise buyers, security leaders, co-investors, and market experts that Holly Ventures routes directly to founders.
Stage Focus
Holly Ventures invests exclusively at the Seed stage, alongside larger institutional leads. The firm participates in rounds of $5–10M in total size. John Brennan emphasizes that he often engages with founders before any formal financing round — at the ideation or pre-product phase.
Check Size
Holly Ventures writes smaller, collaborative checks as a non-lead in seed rounds of $5–10M. Given the $33M fund size and solo-GP model, typical individual checks are likely in the $500K–$2M range, preserving significant reserves for follow-on.
Lead Tendency
Holly Ventures is a follower, intentionally designed to invest alongside larger lead investors rather than compete for lead positions. Lead investors in Holly's portfolio to date include Index Ventures, Notable Capital, Team8, Cyberstarts, Sequoia, General Catalyst, and Foundation Capital.
Recent Activity & Fund Status
Holly Ventures launched Fund I ($33M) on December 9, 2025 and is actively deploying. As of the fund launch, six investments had already been made, two of which had already progressed to Series A. Key recent portfolio news:
- February 2026: Portfolio company Astelia raised a $35M Series A
- February 2026: Portfolio company Venice featured in press for PAM innovation
- December 2025: Fund I officially launched with $33M
Portfolio Companies
Two portfolio companies are publicly disclosed:
-
Astelia (astelia.io) — AI-native exposure management platform using agentic AI and real network topology mapping to surface the ~2% of vulnerabilities that are truly reachable and exploitable. Founders: Alon Noy (Neuhaus), Nadav Ostrovsky, Roy Rajwan. Raised $35M Series A (Feb 2026).
-
Venice (venice.io) — Modern Privileged Access Management (PAM) built for Zero Standing Privilege with Just-in-Time access across cloud and on-prem environments. Founders: Rotem Lurie, Or Vaknin.
Four additional investments remain undisclosed as of fund launch.
Team
John Brennan — Founder & Managing Partner John Brennan is the sole GP of Holly Ventures. Previously a Senior Partner at YL Ventures (prominent Israeli-focused cybersecurity fund), he also held roles at DCVC, OCA Ventures, and Horsley Bridge Partners. His background spans both the U.S. and Israeli cybersecurity ecosystems. He holds an MBA from the University of Chicago Booth School and a BS from Trinity College in Connecticut.
Brennan's track record includes early involvement with Medigate (sold to Claroty for $400M in 2022) and board membership at MIND (founded by Eran Barak, previously co-founded Hexadite, acquired by Microsoft in 2017).
LinkedIn: https://www.linkedin.com/in/jbrennan09/
Decision Process
Solo GP — John Brennan makes all investment decisions. Founders interact with Brennan directly from day one, which is a deliberate competitive differentiator.
Founder Preferences
Holly Ventures seeks founders with deep expertise and ambition to tackle massive cybersecurity challenges, paired with humility and grit for relentless execution. Brennan looks for founders with real buyer/security leader relationships — solving problems CISOs actually care about. He values technical founders with deep domain knowledge, often from Israeli unit 8200 or U.S. enterprise security backgrounds.
Geographic Focus
US and Israel are the two primary geographies. San Francisco/Bay Area and Israeli (Tel Aviv) tech ecosystems. The firm invests globally but has a stated emphasis on Israel.
LP Base & Network
LPs include: Bessemer Venture Partners, Ballistic Ventures, CRV, Wing VC, IVP, TCV, Notable Capital, Team8, Brightmind, Ten Eleven Ventures, Vanderbilt University, Okta Ventures. This LP syndicate is itself a major source of value delivery to portfolio companies.
Values
- People first — Long-term partnership through full company lifecycle
- Solving real problems — Works with real buyers to identify most critical challenges
- Collaborating to win — Writes smaller checks; works well with top-tier security investors of all sizes