Michael O'Connor (born 27 October 1965) is an English costume designer. He has been nominated for the Academy Award for Best Costume Design three times, winning for The Duchess (2008).

O'Connor was born in London, England. He began his training as a dresser at the Old Vic and then spent six years in a costume house before deciding to go freelance.^[1]

In the 1990s, O'Connor went into the film industry. His early works as a wardrobe supervisor was on such films as The House of the Spirits (1993) and Emma (1996). Then he was elevated to an assistant costume designer and worked in this role on several notable films, these include Oscar and Lucinda (1997), Topsy-Turvy (1999), and Quills (2000). In addition, he was an associate costume designer on Harry Potter and the Chamber of Secrets (2002).

After working as costume designer on several minor British films, he came to prominence with his work on Tom Brown's Schooldays, a TV movie for ITV. He then worked on his most high-profile film up until then, the film version of Giles Foden's bestselling novel, The Last King of Scotland. He then worked on Brick Lane as well as Miss Pettigrew Lives for a Day.

He came to the attention of the film industry in 2009, when he received the Academy Award for Best Costume Design,^[2] the BAFTA Award for Best Costume Design^[3] as well as the Satellite Award for Best Costume Design^[4] for The Duchess.

In 2014, he started working on costumes for Tulip Fever.^[5]

In 2021, he was nominated for another BAFTA Award for Best Costume Design for his work on Ammonite.^[6]