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Sean Grennan

Acting
Updated: May 09, 2026
3Total Films
7.8 Highest Rated
Birth Place: Chicago, Illinois, U.S.

About Sean Grennan

An actor for many years, Sean began writing for the theatre as co-librettist for the musical Phantom of the Country Opera, which had its world premiere at the Marriott Theatre in Lincolnshire, Illinois. He went on to debut five shows at the American Heartland Theatre in Kansas City –his comedies Beer for Breakfast and As Long As We Both Shall Live and his musicals (librettist/lyricist) Married Alive!, A Dog’s Life, and Another Night Before Christmas. In addition, Sean has had four world premieres at Peninsula Players Theatre in Wisconsin — Making God Laugh, The Tin Woman, Now and Then and A Rock Sails By. The last of which was part of the statewide festival, “World Premiere Wisconsin”. His play LUCK! won an honorable mention from the National Writers Association’s Playwrighting Festival and was produced by the Epic Theatre Company. His plays and musicals have gone on to hundreds of productions around the world, including China, England, Australia, Germany, Serbia, Russia, Ireland, Italy, and others. Sean has been the Playwright in Residence at Centre Stage’s New Play Festival in South Carolina, the Playwright in Residence at Lamb Arts Regional Theatre in Iowa and twice served as an adjudicator for the Midwest Dramatists Conference. Longtime Chicago and New York City residents, Sean and his wife Kathy moved full time to Pennsylvania in ’22 when Kathy completed a 13-year run in Broadway’s “Wicked.” In PA, they share a lovely home, canoe, and golf cart, as well as sweet memories of Sean’s recently passed on writing partner, excellent dog Hank. His musical “Phantom of the Country Opera” has been published by MTI, and his other plays/musicals have been published by Playscripts, Inc. and Broadway Licensing. Sean is a proud member of Actors’ Equity Association, SAG/AFTRA and The Dramatists Guild.

Sean Grennan Movies & Career Overview

The filmography of Sean Grennan reflects a strong mix of popular and critically appreciated roles. Across 3 major appearances, the actor has built a reputation through performances in multiple genres and storytelling styles.

Dominant Genre

A large portion of Sean Grennan's work falls within the History genre, where audiences tend to respond most strongly to their on-screen presence.

Success Ratio

Approximately 67% of Sean Grennan's films maintain ratings above 6.5, indicating a consistent level of audience approval.

One of the most highly rated entries in their career remains The Untouchables, which stands out as a key performance.

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Best Sean Grennan Movies Ranked

Must-watch hits from Sean Grennan's career based on audience ratings.

Full Filmography

Every movie Sean Grennan has appeared in, with audience ratings and verdicts.

YearMovieCharacterSuccessMore
1993 Rudy High School Assistant Coach Hit Similar →
1987 The Untouchables Cop Cousin Super Hit Similar →
1985 Interviews With Interviewers… About Interviewing Self Flop Similar →

Sean Grennan - Frequently Asked Questions

What is the best movie of Sean Grennan?

According to audience ratings, the best movie starring Sean Grennan is "The Untouchables" with a rating of 7.8/10.

How many movies has Sean Grennan acted in?

Sean Grennan has been featured in at least 3 major films throughout their career.

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