Costello was born in Pittsburgh, Pennsylvania to Irish immigrants Ellen (née Fitzgerald; born 1853) and Thomas Costello (born 1852).
He made his film debut in 1908, but was long believed to have debuted in Adventures of Sherlock Holmes; or, Held for Ransom (1905), supposedly playing the lead in what is regarded as the first serious film to feature the character of Sherlock Holmes, since it was preceded only by the 30-second comedy film Sherlock Holmes Baffled (1900).
However, Holmesian scholar Leslie S. Klinger has written that the identification of Costello in the role is flawed.
Klinger states that the first identification of Costello with the role was in Michael Pointer's Public Life of Sherlock Holmes published in 1975 but Pointer later realized his error and wrote to Klinger stating
"I am now aware that Maurice Costello could not have been in that film, as he had not joined the Vitagraph company by that date.
I'm sorry that my book has been misleading, but I doubt that I shall have the opportunity for an amended reprint, and should not have the time to prepare one anyway."

Costello joined Vitagraph, being a member of the first motion picture stock company ever formed, playing opposite Florence Turner.
Among some of his best known pictures are A Tale of Two Cities, The Man Who Couldn't Beat God and For the Honor of the Family.
After an absence of some years he returned to the screen.
He was married to actress Mae Costello (née Altschuk).
His descendants include two daughters, actresses Dolores Costello and Helene Costello, a grandson John Drew Barrymore, and a great granddaughter Drew Barrymore.
He was one of the world's first leading men in early American cinema, but like a lot of other silent screen stars, he found the transition to "talkies" extremely difficult, and his leading man status was over.
However, Costello was a trouper, and continued to appear in movies, often in small roles and bit parts, right up until his death in 1950.

On November 23, 1913, Costello was arrested for beating his wife Mae.
On November 25, 1913, Costello admitted that he had beaten his wife while intoxicated.
Mae Costello requested that the charges be dropped to disorderly conduct, and Costello was given six months probation by Magistrate Geisner of the Coney Island Police Court.

Maurice Costello also discovered Moe Howard of the Three Stooges, who, as a teenager, ran errands and got lunches for the actors at the Vitagraph Studios at no charge.
This impressed Costello who brought him in and introduced him to other leading actors of the day.
Moe then gained small parts in many of the Vitagraph movies but most of these were destroyed by fire that swept the studios in 1910.

Costello died at the age of 73 in 1950 in Los Angeles, California of a heart problem and was interred at Calvary Cemetery, East Los Angeles, a Catholic cemetery.
Costello was born in Pittsburgh, Pennsylvania to Irish immigrants Ellen (née Fitzgerald; born 1853) and Thomas Costello (born 1852). He made his film debut in 1908, but was long believed to have debuted in Adventures of Sherlock Holmes; or, Held for Ransom (1905), supposedly playing the lead in what is regarded as the first serious film to feature the character of Sherlock Holmes, since it was preceded only by the 30-second comedy film Sherlock Holmes Baffled (1900). However, Holmesian scholar Leslie S. Klinger has written that the identification of Costello in the role is flawed. Klinger states that the first identification of Costello with the role was in Michael Pointer's Public Life of Sherlock Holmes published in 1975 but Pointer later realized his error and wrote to Klinger stating
"I am now aware that Maurice Costello could not have been in that film, as he had not joined the Vitagraph company by that date. I'm sorry that my book has been misleading, but I doubt that I shall have the opportunity for an amended reprint, and should not have the time to prepare one anyway."
Costello joined Vitagraph, being a member of the first motion picture stock company ever formed, playing opposite Florence Turner. Among some of his best known pictures are A Tale of Two Cities, The Man Who Couldn't Beat God and For the Honor of the Family. After an absence of some years he returned to the screen. He was married to actress Mae Costello (née Altschuk). His descendants include two daughters, actresses Dolores Costello and Helene Costello, a grandson John Drew Barrymore, and a great granddaughter Drew Barrymore. He was one of the world's first leading men in early American cinema, but like a lot of other silent screen stars, he found the transition to "talkies" extremely difficult, and his leading man status was over. However, Costello was a trouper, and continued to appear in movies, often in small roles and bit parts, right up until his death in 1950.
On November 23, 1913, Costello was arrested for beating his wife Mae. On November 25, 1913, Costello admitted that he had beaten his wife while intoxicated. Mae Costello requested that the charges be dropped to disorderly conduct, and Costello was given six months probation by Magistrate Geisner of the Coney Island Police Court.
Maurice Costello also discovered Moe Howard of the Three Stooges, who, as a teenager, ran errands and got lunches for the actors at the Vitagraph Studios at no charge. This impressed Costello who brought him in and introduced him to other leading actors of the day. Moe then gained small parts in many of the Vitagraph movies but most of these were destroyed by fire that swept the studios in 1910.
Costello died at the age of 73 in 1950 in Los Angeles, California of a heart problem and was interred at Calvary Cemetery, East Los Angeles, a Catholic cemetery.
Maurice Costello