John Brennan

Senior Partner at YL Ventures

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Biography

John Brennan was Senior Partner at YL Ventures, where the firm's own site says he oversaw its core U.S. investment processes and portfolio value-add work from Silicon Valley and managed its Venture Advisory Board of more than 120 cybersecurity experts. Before YL Ventures he held roles at Data Collective (DCVC), OCA Ventures and Horsley Bridge Partners, and began his career as a consultant at Accenture. He holds an MBA from the University of Chicago and a B.S. from Trinity College in Connecticut. In December 2025 he launched Holly Ventures, a solo-GP cybersecurity seed fund, and is no longer listed on the YL Ventures team page.

Education

Previous Experience

Notable Investments

Eureka Security

Career Timeline

2022
Announced YL Ventures leading an 8 million dollar seed round in Eureka Security, a cloud data security posture management company.
2025
Launched Holly Ventures, a 33 million dollar solo-GP cybersecurity seed fund, after leaving YL Ventures.

Sources & References

YL Ventures - Team Focus: John Brennan ↗YL Ventures - John Brennan: YL Ventures leads $8M Seed Round in Eureka ↗RSAC Conference - John Brennan speaker profile ↗Holly Ventures Launches $33M Cybersecurity Fund (press release) ↗