Marcel Thomas Rooney (born September 20, 1937) is an American Benedictine monk, abbot, liturgist, musician, and author.

"[2] For many years Rooney taught at Conception Seminary sponsored by his home abbey and served as President of the Liturgical Commission of the Diocese of Kansas City-St. Joseph, MO.

[4] While his tenure as Abbot Primate was brief, Rooney's most notable work was his assignment by Pope John Paul II to investigate the allegations of sex abuse by Cardinal Hans Hermann Groër who had served as the archbishop of Vienna for nine years until his retirement in 1995.

[8] In 2011, Rooney sought to develop the "Saint Gregory Institute of Pastoral Liturgy, Music, and Art" at the Durward's Glen retreat center in the Diocese of Madison, Wisconsin, at the invitation of Bishop Robert C.

[10][11] In addition to his many articles and book publications, Rooney continues to reside in the Madison, WI, where he offers his priestly and liturgical services to parishes and the diocese.