John Brennan

Founder & Managing Partner at Holly Ventures

📍 San Francisco Bay Area, United States🔄 Updated September 2026💼 26 investments📅 10 years investing🗓 Last invested Feb 2025𝕏 @upgrade_to_unlock
VC🌍 United States20+ investments
26
Total investments
19
Early stage
0
Mid stage
0
Late stage
10y
Years active

Portfolio

25 investments · sorted by recency
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Seed Investor
Feb 2025
Glow is the Endpoint AI company. AI has changed how people work, creating a new generation of risks that traditional reactive tools can’t keep up with. Were rethinking endpoint security from the ground up: an AI-powered operating model built on prevention, not reaction, that fixes the foundation so organizations can adopt new software and AI on solid ground. Learn more at glow.io.
Seed Investor
Jan 2025
Astelia is an AI-native exposure management platform that enables organizations to focus exclusively on vulnerabilities that are truly reachable and exploitable in their environment. By mapping real network topology and applying agentic AI to analyze exploit requirements, Astelia replaces vulnerability guesswork with predictive analysis. It eliminates noise, surfaces the ~1% of vulnerabilities that actually represent real exposure, and delivers evidence-based remediation guidance beyond patching. The result is faster, more practical mitigation that aligns security and IT while saving time and resources.
Seed Investor
Jul 2024
Beacon is the security data management platform that helps modern security teams escape the tradeoff between coverage, context, and cost. With Beacon, you can seamlessly collect, reduce, enrich, and route your security data – so analysts and AI agents have the context and visibility to focus on security, not data wrangling. The result: cleaner data, faster investigations, and smarter security at scale.
Seed Investor
Jan 2024
Venice is a modern Privileged Access Management platform built for today’s reality. We help organizations move to Zero Standing Privilege with Just-in-Time, contextual access across cloud and on-prem environments - with no vault sprawl, no rigid workflows and no agent. Designed to be used, Venice makes privilege temporary, auditable, and ready for the speed and scale of AI-driven systems.
Seed Investor
Mar 2023
MIND is on a mission to help organizations thrive in a digital world by protecting their most sensitive information. MIND is the first AI-native data security platform that puts data loss prevention (DLP) and insider risk management (IRM) programs on autopilot to autonomously find sensitive data, fix data risk issues and stop data leaks at machine speed across SaaS applications, Gen AI tools, endpoints, on-premises file shares and email systems. Our goal is to help our customers achieve Stress-Free DLP. The platform leverages MIND AI, our multi-layer classification engine, to analyze billions of data events in real-time, deliver context-aware risk assessments, enable automated remediation actions and block data loss on endpoints. We enable businesses to mind what really matters—their most sensitive data. Founded and led by cybersecurity leaders and industry veterans, MIND is based out of Seattle, WA. For more information, contact us at info@mind.io.
Seed Investor
Jan 2023
Miggo is the first Application Detection and Response (ADR) platform on a mission to stop application breaches. 80% of all cyber incidents happen in the application layer, however too many are being slipped by existing tools due to a blindspot to the actual application behavior. By using in-application runtime context, Miggo maps how applications actually operate in runtime, identifies high-risk application flows, pinpoints the weak spots, and provides real-time detection and response capabilities in the application layer.
Seed Investor
Oct 2022
Gutsy is a security process fabric that unifies intel from across your vulnerability management program and helps you prioritize vulnerabilities, accelerate remediation, and drive accountability. Gutsy connects to your existing systems, unifies and enriches data from them, uses AI to identify the most critical risks, and provides dashboards and reports.
Seed Investor
Jul 2022
Were now part of Cato Networks! Were as committed as ever to helping organizations secure their AI transformation by securing and governing every AI interaction, from 3rd party AI usage to homegrown AI-powered applications and agents. AI Security is available as part of the Cato Platform as either a stand-alone offering or in combination with other SASE capabilities. For all the latest - make sure to follow @cato-networks on LinkedIn or visit www.catonetworks.com
Seed Investor
Jul 2022
This company is now part of Okta! Stay connected by following Oktas Linkedin for the latest news and insights
Seed Investor
Feb 2022
Opus Security set out to transform vulnerability management by bringing automation and intelligence into one of the hardest problems in cybersecurity: remediation. Our platform was built around a fleet of AI-driven security agents designed to analyze, prioritize, and remediate vulnerabilities at scale. By embedding expertise into existing IT, engineering, and security workflows, Opus aimed to remove manual bottlenecks and make vulnerability management proactive, continuous, and seamless. The mission was simple: reduce backlog, eliminate wasted cycles, and help organizations stay ahead of risk with always-on security operations.
Seed Investor
Oct 2021
Delivering cloud data security to companies is what Eureka Security is all about. If you store sensitive data in clouds such as AWS, Azure, GCP, and Snowflake, our DSPM solution will help your security team understand where data is, the type of data it is, learn who and what can access it, and keep it continuously secure. Our SaaS platform is easy-to-deploy and can be spun up in minutes for actionability on day one. In an age where data breaches are occurring far too often and security leaders desperately need a real-time look at risks, our mission is to help our customers achieve their “Eureka!” moment - find and secure all data risks in the cloud without slowing down the business.
Seed Investor
Jun 2021
Piiano builds data security infrastructure for developers. Piiano Vault is developed by former IDF cybersecurity experts. Bringing together decades of experience in hacking, engineering and software management capabilities. Our innovative Vault runtime protection technology stops data theft in production environments. Talk to us to find out how!
Seed Investor
Jun 2021
Valence protects organizations from threats created by SaaS and AI sprawl. By unifying SaaS discovery, SSPM, AI security, and ITDR, Valence delivers the comprehensive coverage needed to find and fix SaaS and AI risks. The platform uncovers shadow AI and AI agents, flags misconfigurations before they become incidents, and detects unusual activity across human and service identities. Valence goes beyond visibility with one-click remediation, automated workflows, and guided collaboration to help security teams operationalize their SaaS and AI security programs. Trusted by leading organizations, Valence enables secure SaaS and AI adoption.
Seed Investor
Jan 2021
Grip Security is the industry-leading SaaS security platform, pioneering the way organizations identify, investigate, remediate, and automate SaaS and GenAI risks. Grip delivers complete control over every application, sanctioned or shadow, while driving cost savings by eliminating unnecessary accounts, duplicate deployments, and unused licenses.
Seed Investor
Aug 2020
Enso is the first Application Security Posture Management (ASPM) solution, helping security teams everywhere eliminate their AppSec chaos with application discovery, classification and management. Founded by application security experts, Enso easily deploys into enterprise environments to create an actionable, unified inventory of all application assets, their owners, security posture and associated risk. With Enso security, any AppSec team can build a simplified, agile and scalable application security program. For more information, visit enso.security. Follow us on Twitter: https://twitter.com/enso_security
Show all 25 investments ↓
Experience · 31 entries
All (31)
Investments (26)
Founder (1)
2025
Seed Investor
Feb 2025
Glow is the Endpoint AI company. AI has changed how people work, creating a new generation of risks that traditional reactive tools can’t keep up with. Were rethinking endpoint security from the ground up: an AI-powered operating model built on prevention, not reaction, that fixes the foundation so organizations can adopt new software and AI on solid ground. Learn more at glow.io.
Seed Investor
Jan 2025
Astelia is an AI-native exposure management platform that enables organizations to focus exclusively on vulnerabilities that are truly reachable and exploitable in their environment. By mapping real network topology and applying agentic AI to analyze exploit requirements, Astelia replaces vulnerability guesswork with predictive analysis. It eliminates noise, surfaces the ~1% of vulnerabilities that actually represent real exposure, and delivers evidence-based remediation guidance beyond patching. The result is faster, more practical mitigation that aligns security and IT while saving time and resources.
2024
Seed Investor
Jul 2024
Beacon is the security data management platform that helps modern security teams escape the tradeoff between coverage, context, and cost. With Beacon, you can seamlessly collect, reduce, enrich, and route your security data – so analysts and AI agents have the context and visibility to focus on security, not data wrangling. The result: cleaner data, faster investigations, and smarter security at scale.
Founder & Managing Partner
Jan 2024
Holly Ventures invests exclusively in seed stage founders tackling the cybersecurity industry’s biggest challenges.
Seed Investor
Jan 2024
Venice is a modern Privileged Access Management platform built for today’s reality. We help organizations move to Zero Standing Privilege with Just-in-Time, contextual access across cloud and on-prem environments - with no vault sprawl, no rigid workflows and no agent. Designed to be used, Venice makes privilege temporary, auditable, and ready for the speed and scale of AI-driven systems.
Show all 31 entries ↓
Investment activity
2016–2025 · 26 investments
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