California is home to some of the most dynamic and innovative organizations in the world, from cutting-edge biotech firms to top-tier universities and Silicon Valley tech giants. Leading the charge in safeguarding these organizations’ critical assets are the state’s top Chief Information Security Officers (CISOs). These leaders not only protect against evolving cyber threats but also shape security strategy, foster innovation, and mentor the next generation of cybersecurity talent.
In this list, we highlight 10 CISOs to watch in California, professionals making a significant impact across industries and setting new standards for excellence in information security.
Krishnan Chellakarai — Gilead Sciences
Krishnan Chellakarai leads information security, risk, and compliance at Gilead Sciences in Foster City, California, bringing over 30 years of experience in biotech, finance, and technology. He was the 2025 BayAreaCISO ORBIE Super Global Winner, a prestigious recognition for security leaders in large, multi-national organizations.
Beyond his corporate role, Chellakarai is also deeply invested in cultivating cyber talent: he co-founded NextGen Cyber Talent, a nonprofit focused on increasing diversity and inclusion in cybersecurity.
Monte Ratzlaff — University of California System
Monte Ratzlaff is the systemwide Chief Information Security Officer for the University of California (UC) system. He has been a cornerstone of UC’s security operations since 2010, and he launched the UC Cyber-risk Coordination Center (now UC Digital Risk & Security) in 2015. Under his leadership, UC has developed shared cybersecurity metrics, strengthened governance, and expanded threat-intelligence sharing across its campuses.
Jeffrey Aguilar — Hoag Health System
Jeffrey Aguilar serves as CISO at Hoag Health System, a nonprofit healthcare network in Orange County, California. He was named 2025 Southern California CISO of the Year by SIM (Southern California Society for Information Management), recognizing his visionary leadership and strong commitment to security resilience.
Aguilar’s journey is notable: he previously served as CISO for Los Angeles County and has decades of experience in both public sector security and consulting.
David Tugwell — Agilent Technologies
David Tugwell has been serving as AVP and CISO at Agilent Technologies, based in Santa Clara and Walnut Creek, California, for over a decade. He frequently represents Agilent at peer CISO events; for instance, he was a speaker at the Gartner CISO Circle Lunch on how security and privacy leaders can collaborate to achieve better outcomes. Tugwell’s long tenure and his ability to bridge business and technical risk make him a steady, respected figure in the Bay Area security community.
Auston Davis — City of San José
Auston Davis is the Chief Information Security Officer (CISO) for the City of San José, overseeing cyber risk and protecting municipal infrastructure across 7,000+ city employees. Before this role, he served in senior security positions at Stanford Children’s Health, Kaiser Permanente, HeartFlow, and even held a long military career in the U.S. Air Force. Davis has been honored as a Top 10 Information Security Professional by the Cyber Defense Group (2023 and 2024) and was on Becker’s “Top 25 CISOs to Know” list in earlier years.
Upendra Mardikar — EVP & CISO, TIAA
Upendra Mardikar holds the role of EVP & CISO at TIAA, a major financial services firm with offices in San Francisco. He was recognized with the Large Enterprise ORBIE Award at the 2025 BayAreaCISO ORBIE Awards for his leadership in a high‑revenue, complex organization.
Leda Muller — Stanford University (R&DE)
Leda Muller is the Chief Information Security & Privacy Officer for Stanford University’s Residential & Dining Enterprises (R&DE). With over 25 years of experience, she leads a unique portfolio that includes cybersecurity, privacy, digital accessibility, and PCI strategy. In 2023, she was honored at the Champions in Security Awards for her commitment to community, innovation, and mentorship, an acknowledgment of her human-centered leadership.
Allison Henry — University of California, Berkeley
Allison Henry is the Chief Information Security Officer at UC Berkeley, one of California’s most prestigious public research universities. Under her leadership, UC Berkeley’s security office has re-architected identity systems, improved third‑party risk management, and fostered a shared-responsibility security model across campus.
Bryan Green — Andreessen Horowitz (a16z)
Bryan Green is CISO of Andreessen Horowitz (a16z), the prominent Silicon Valley venture capital firm headquartered in Menlo Park, California. With a long track record across sectors, including time at Zscaler and Salesforce, he brings deep industry knowledge to securing a fast-moving, high-risk investment environment.
Atticus Tysen — Intuit
Atticus Tysen leads information security and fraud prevention at Intuit, based in Mountain View, California. At the 2025 BayAreaCISO ORBIE Awards, he was honored with the Leadership ORBIE, highlighting his contributions to driving security innovation in a fast-moving fintech company. Tysen has a strong technical and product background, having previously served as a long-time CIO within Intuit before expanding into security leadership.
What Makes a CISO “One to Watch”
The role of a CISO has evolved dramatically from technical gatekeeper to strategic leader. The CISOs above stand out not just for their titles, but for real impact: building mature security programs, influencing culture, earning industry honors, and guiding organizations through digital transformation. Whether you’re writing for a general audience or a cyber‑savvy readership, these ten leaders in California offer compelling stories of innovation, resilience, and influence.