Her mother, Kathleen Ann (Craft), is a homemaker and a philanthropist. Her father, Martin Joseph Holmes, Sr., is a lawyer, an attorney specializing in divorces.
Voted as "Babe of the Year 98" (Årets Babe 98) by Expressen Fredag, Sweden.
Graduated from Notre Dame Academy, an all-girls Roman Catholic school in Toledo, Ohio.
Chosen as one of Teen People Magazine's "21 Hottest Stars Under 21". 
Deferred attending Columbia University twice, but finally took a single photography class in the summer of 2000.
Bought a Wilmington, North Carolina townhouse, while filming Dawson's Creek (1998), and lived there for ten months of the year.
Turned down the lead role in 40 Days and 40 Nights (2002), due to scheduling conflicts.
Auditioned for the role of Ellie Christianson in Wicked (1998), but Julia Stiles won the part.
A small band from Japan have performed a song about her entitled "Katie".
Was lined up to have a 3 episode guest spot on Friends (1994) but had to pull out due to scheduling conflicts.
Likes to run three to four miles a couple of times a week to clear her head.
The first movie she ever saw was E.T. the Extra-Terrestrial (1982).
Her fantasy role was playing Sydney in Scream 3 (2000).
The first concert she ever saw was Whitney Houston.
Her favorite movie is My Best Friend's Wedding (1997).
Sang Eponine's theme song, "On My Own" from Les Miserables, in an episode of Dawson's Creek (1998).
Three older sisters: Tamera Jean (B. 1967), Holly Ann (B. 1969), and Nancy Kay (B. 1974). One older brother: Martin Joseph, Jr. (B. 1970), who works as a lawyer in Ohio.
Noisy underground British artist 'Firexit' has two songs with references to Katie, one called "K H" (Katie's initials) and a song called "The reason I can't have her" featuring samples of Katie singing 'On my own' from a Dawson's Creek (1998) episode.
Auditioned for the role as Buffy Summers in the series Buffy the Vampire Slayer (1997), but was too young.
December 2003 - She and Chris Klein are engaged.
Ranked #35 in Stuff magazine's "102 Sexiest Women in the World" (2002).
Was engaged to actor Chris Klein December 2003 - March 2005. They were together for five years.
Engaged to Tom Cruise as of 17th June 2005.
Has worked with two Batmans. In Batman Begins (2005), she works with Christian Bale. Her previous film was First Daughter (2004), in which her father, the President, is played by Michael Keaton.
Named #22 on the Maxim magazine Hot 100 of 2005 list.
Holmes's couch-jumping-worthy engagement ring is a Edwardian-style oval- shaped diamond ring of about 5 carats in a pave setting.
Ranked as #72 in FHM's "100 Sexiest Women in the World 2005" special supplement. (2005)
Her brother Martin Joseph, Jr. works as a lawyer in Ohio.
Friends with Victoria Beckham.
Named #90 in FHM magazine's "100 Sexiest Women in the World 2006" supplement. (2006).
She and Tom Cruise both wore Armani at their wedding.
On November 18, 2006, married Tom Cruise at the Odescalchi Castle in Lake Bracciano, Italy in front of family and friends. Lots of celebrity guests included Will Smith and Jada Pinkett Smith, Brooke Shields and Chris Henchy, Richard Gere, Victoria Beckham and David Beckham, Jennifer Lopez and Marc Anthony, and Jim Carrey and Jenny McCarthy, John Travolta and Kelly Preston, Jenna Elfman and Bodhi Elfman and Leah Remini.
Ex-stepmother of Tom Cruise's adopted children: Isabella and Connor Cruise.
Best Man at her wedding to Tom Cruise was David Miscavige.
Mentioned in the song, "High School Never Ends", by Bowling for Soup.
Participated in and finished the New York Marathon in 2007.
Almost cast opposite Patrick Wilson (her co-star on Broadway's "All My Sons"), in the film version of The Phantom of the Opera (2004) as Christine Daaé, but was considered too old to play the part.
Katie's brother-in-law Joseph Jeffrey Fretti, the husband of Holmes' eldest sister Tamara Holmes, was found dead on 12 April 2009 in his mother Shirley's home in Sarasota, Florida. He was 48.
Auditioned for the role of Carla Albanese in Nine (2009), but Penélope Cruz was given the part instead.
Had a girlhood crush on Tom Cruise, her future husband, saying once in a magazine interview, "I think every little girl dreams of her wedding. I used to think I was going to marry Tom Cruise".
Gave birth to her 1st child at age 27, a daughter named Suri Cruise on April 18, 2006. Child's father is her boyfriend (now ex-husband), Tom Cruise.
(June 28, 2012) Filed for divorce from her husband of 5 years Tom Cruise.
Her father is of three quarters German and one quarter Irish descent; the family surname, originally "Holm", was changed to "Holmes" by her German immigrant ancestors. Her mother has Irish and English ancestry.
Is back in Wilmington, North Carolina filming the 6th (and probably final) season of Dawson's Creek (1998). [October 2002]
Accepted marriage proposal from Tom Cruise at the Eiffel Tower in Paris. [June 2005]
Filming Batman Begins (2005) in London, England. [April 2004]
Recently announced engagement to actor Chris Klein. [January 2004]
Filming the movie Pieces of April (2003) with Oliver Platt. [April 2002]
Starring on Broadway's "All My Sons" opposite John Lithgow, Dianne Wiest and Patrick Wilson. [September 2008]
Was in a relationship with Joshua Jackson during the series of Dawson's Creek (1998) and remained close friends after the show ended.
Received $ 9.8 million including child support in her divorce settlement from Tom Cruise.
Is the mother of ex-husband Tom Cruise's only biological child, daughter Suri Cruise.
Is the youngest of 5 siblings and the youngest paternal grandchild.
She wears a size 11 shoe.
Contrary to popular belief, her full name is not Katherine or Kathleen.
Is often ridiculed and criticized for what Is considered a terrible career choice on her part, of turning down the chance to reprise her role of Rachel Dawes in The Dark Knight (2008), an Academy Award winning film and one of the highest grossing films of all time, to instead do the critical and financial failure Mad Money (2008).