Colleen M. O'Neil's Profile Image

Colleen M. O'Neil

The Calfee Building, 1405 East Sixth Street Cleveland, Ohio 44114-1607
Firm: Calfee, Halter & Griswold LLP
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Calfee, Halter & Griswold LLP

Years In Practice

Phone Number (216) 622-8530

Colleen O’Neil serves as Co-Chair of Calfee's Litigation practice group. She helps clients resolve complex business disputes.

Colleen has extensive experience in federal and state courts nationwide helping business clients resolve the following types of conflicts:

  • Commercial contract disputes
  • Shareholder and corporate disputes, including post-closing issues
  • Estate and probate matters
  • Trade secret claims
  • Real property disputes
  • Municipal and public law issues
  • Title VII claims

Colleen has counseled and represented businesses, financial institutions and high-net-worth individuals in a variety of corporate, commercial, fiduciary and employment disputes with a results-oriented, practical approach.  

She has successfully prosecuted and defended a variety of business tort claims in both federal and state courts nationwide.

Colleen has represented municipalities and clients in the energy industry in various types of litigation, including contractual disputes, real estate disputes and employment matters.

Colleen has been selected for inclusion to the Ohio Super Lawyers list from 2012-2021. She has also been named to the Top 50 Women Ohio Super Lawyers list from 2013-2021 and as a Top 25 Women Cleveland Super Lawyers list from 2013-2018 and 2020-2021.

She joined Calfee in 1998, and she is a member of the firm’s Practice Planning and Growth Committee and the Diversity & Inclusion Committee. Colleen began serving as Vice Chair of the firm's Litigation practice group in 2019 and Co-Chair in 2021.

What legal services does this lawyer offer?
  • The Best Lawyers in America©, Commercial Litigation (2021-2023)
  • Ohio Super Lawyers (2012-2022)

    • Top 50 Women Attorneys in Ohio List (2013-2022)
    • Top 25 Women Attorneys in Cleveland List (2013-2018; 2020-2022)
    • Top 100 Attorneys in Ohio List (2013-2015)
  • Woman of Professional Excellence Award, YWCA of Greater Cleveland, 2010
Cleveland Marshall College of Law, J.D.
Graduated 1996
John Carroll University, B.A.
Graduated 1992
Contact Details and Office Locations
The Calfee Building, 1405 East Sixth Street
Cleveland, Ohio 44114-1607
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