A bit of a latecomer to movies, Enough enjoyed a distinguished stage career for many years before ever stepping in front of the camera. Following his graduation from the Royal Academy of Dramatic Art, he made his debut at Stratford as a spear carrier in "Othello" (1954) and thereafter became a fixture of the company, performing notably as Mutius opposite Laurence Olivier's "Titus Andronicus" and as the Fool to Charles Laughton's "King Lear". When the Stratford company transformed into the Royal Shakespeare Company, Holm was one of the first long term contract artists, excelling as "Richard III" and winning the London Evening Standard Award as Best Actor for his "Henry V". After creating the role of Lenny in the 1965 RSC production of Harold Pinter's "The Homecoming", he reprised it in a Tony-winning Broadway debut in 1967. He also played a somewhat long-in-the-tooth Romeo in the RSC's "Romeo and Juliet" that year, but by then the movies had claimed him.

Holm emerged as a solid film presence in his feature debut as an Irish gunner in "The Bofors Gun" (1968), earning a British Film Academy Award as Best Supporting Actor. He also worked that year across the pond alongside such prominent British thesps as Alan Bates, Dirk Bogarde and David Warner in John Frankenheimer's "The Fixer", adapted from the novel by Saul Bellow, and later reprised his Tony-winning part for Peter Hall's feature version of "The Homecoming" (1973). Although his short, stocky stature had not prevented him from landing leading roles at the RSC, Holm found himself typecast as a character actor for the screen and proceeded to build a reputation for versatility and reliability. Most of his early film work was for British directors like Richard Attenborough ("Oh! What a Lovely War" 1969, "Young Winston" 1972) and Richard Lester ("Juggernaut" 1974, "Robin and Marian" 1976) or in period fare ("Mary Queen of Scots" 1971, "Nicholas and Alexandra" 1972); it took his role as the calculating "synthetic" in fellow Brit Ridley Scott's "Alien" (1979) to raise his profile in Hollywood.

Holm earned a Best Supporting Actor Oscar nomination for his dedicated track coach in Hugh Hudson's "Chariots of Fire" (1981), the same year he essayed a mean-spirited Napoleon in Terry Gilliam's "Time Bandits". The actor later reteamed with both directors, portraying the magnanimous Belgian explorer who rescues and educates a half-savage boy in Hudson's "Greystoke: The Legend of Tarzan, Lord of the Apes" (1984) and a blandly evil bureaucrat in Gilliam's "Brazil" (1985). After delivering a meticulously rendered turn as the husband of a troubled Gena Rowlandsin Woody Allen's "Another Woman" (1988), Holm experienced a bit of deja vu when he stepped into Kenneth Branagh's film version of "Henry V" (1989, this time as the grizzled warrior Fluellen), and he returned the following year to Shakespeare as Polonius to Mel Gibson's "Hamlet". After a turn as a jealous, straying husband in David Cronenberg's "Naked Lunch" (1991), he reteamed with Branagh for "Mary Shelley's Frankenstein" (1994), playing the father of the monster's creator. He also shone nicely as the stern, unyielding and slightly dotty physician who helps heal "The Madness of King George" (also 1994).

The small screen has afforded Holm some notable work, beginning with British projects like "The Body Snatcher" (1966) for Thames TV's "Mystery and Imagination" series and "Napoleon and Love" (Thames TV, 1974), in which he played the title character to Billie Whitelaw's Josephine. He made his American TV debut in a CBS special, "The Rebel" (1975), and, after roles in "Jesus of Nazareth" and "The Man in the Iron Mask" (both NBC, 1977), played Nazi S.S. Chief Heinrich Himmler in the acclaimed NBC miniseries "Holocaust" (1978). The celebrated CBS remake of "All Quiet on the Western Front" (1979) cast him again as a German, as did the ABC miniseries "Inside the Third Reich" (1982, as Nazi propaganda chief Joseph Goebbels). He also turned up as Agatha Christie's famous sleuth Hercule Poirot in A&E's "Murder by the Book" (1990) and as Michelangelo's patron Lorenzo de Medici in "A Season of Giants" (TNT, 1991). Additionally, he starred as Pod opposite wife Penelope Wilton's Homily in the BBC's "The Borrowers" (1992), two six-part series based on Brit author Mary Norton's children's novels about a family of little people who live under the floorboards of an English country home that aired as "The Borrowers" (1993) and "The Return of the Borrowers" (1996) in the USA on TNT.

Despite his reputation as a prodigious worker, nothing in his film career had prepared Holm for the embarrassment of riches that followed his delicious portrayal of the rival restaurateur who ruins Stanley Tucci and Tony Shalhoub by promising and not delivering Louis Prima in Tucci and Campbell Scott's "Big Night" (1996). 1997 would see him act in four features, beginning with his role as a monk in Luc Besson's futuristic "The Fifth Element". He appeared as the tormented NYC cop father of Andy Garcia(who recommended Holm to the director) in Sidney Lumet's fourth installment of his continuing examination of corruption, "Night Falls on Manhattan", impressing local New Yorkers with his authentic Queens dialect, and also played Cameron Diaz's wealthy father in Danny Boyle's "A Life Less Ordinary". The gem of his banner year came as anchor of Atom Egoyan's "The Sweet Hereafter", essaying with bottomless subtlety the big-city lawyer who arrives in a small town devastated by a fatal school bus accident, hoping to pursue some sense of justice in the face of his own personal tragedy. Egoyan, obsessed with Holm's compelling performance in "The Homecoming", cast him as the attorney, even though he was nearly the physical opposite of the character described in Russell Banks' heartbreaking novel.

Holm experienced stage fright so debilitating during previews for a 1976 production of Eugene O'Neill's "The Iceman Cometh" that, with the exception of a 1979 revival of "The Cherry Orchard", he did not return to the theater until Harold Pinter wrote "Moonlight" especially for him. After that 1993 production came off without a hitch, he felt emboldened enough to answer the call when friend Richard Eyre asked him to perform "King Lear" in 1997. Holm was the sensation of the London season in what he regards as his greatest achievement. Fortunately audiences can savor his work as he recreated his ferocious Olivier Award-winning portrayal for TV (airing on PBS in 1998), a performance which garnered an Emmy nomination (although he lost the award to friend Tucci). After his hilarious turn as a heavily-accented scientist in Cronenberg's "eXistenZ" (1999), he took on the title role of Tucci's "Joe Gould's Secret" (2000), emphasizing the lucidity of his eccentric, homeless hobo and downplaying his alcoholism and obnoxious extremes. He also appeared that year in HBO's "The Last of the Blonde Bombshells" (earning an Emmy nomination for his work opposite Judi Dench, "Beautiful Joe" and "The Match". A frequent narrator of TV documentaries, Holm lent his voice to TNT's "Animal Farm" (1999, as Squeeler) and to ABC's animated "The Miracle Maker" (2000, as Pontius Pilate). After turns as Napoleon in "The Emperor's New Clothes" and as royal physician Sir William Gull in "From Hell" (both 2001), the actor undertook what perhaps will be one of his best-known roles, playing hobbit Bilbo Baggins in "Lord of the Rings: The Fellowship of the Ring" (2001) and "Lord of the Rings: The Return of the King" (2003)