Owen O'Sullivan
Managing Partner
Owen O’Sullivan is the Managing Partner of William Fry and former Head of our Litigation & Investigations Department.
- [email protected]
- VCard
- Dublin - Head Office

Owen specialises in commercial disputes, particularly shareholder and investment disputes, as well as disputes in the financial sector. He has been involved in many high profile property disputes and has product liability defence experience in the pharmaceutical, energy drink, motor and tobacco sectors.
Recent significant work includes advising:
- Horizon Sports Management on the defence of the claim brought against it by golfer Rory McIlroy and the prosecution of its counterclaim.
- Alternative Advantage plc in Commercial Court proceedings for the return of over €100m sub-custodied to Bernard Madoff
- Tesco on its contractual dispute relating to the development of a new district centre store at Carrickmines.
- Davy Stockbrokers both on its successful Supreme Court challenge to a decision by the Financial Services Ombudsman and ongoing defence of Credit Union litigation
- DCC plc through its High and Supreme Court insider dealing action brought by Fyffes plc and the subsequent Inspectorship process
Owen served as a member of the Law Society’s Litigation Committee for six years and is currently a member of the International Bar Association, the Steering Committee of the Commercial Litigation Association of Ireland and DRI Europe.
Ranking & Recommendations
2023 Chambers Europe
“Owen O'Sullivan is an astute lawyer and a calm and steady influence in difficult circumstances.”

2021 Chambers Global
Sources note his presence in "market-leading commercial litigation" and praise his ability to lead complex claims.

2020 Chambers Europe
Owen garners widespread praise for his expertise in shareholder disputes and regulatory enforcement actions. "He is surgical in his approach; he can pick a case apart to find the strengths and weaknesses," says one impressed interviewee.
2020 Chambers Europe
Another source notes: "He understands all of the issues involved in going to court and is good at explaining those issues."
2023 Legal 500 EMEA
Owen O’Sullivan – Extremely practical and client user friendly.

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