William Hanna was one half of one of the most important partnerships in cartoon history - Hanna-Barbera. He and Joseph Barbera revolutionised the art of cartooning and made television the natural home for cartoons. Not only did they create Tom and Jerry, the most enduringly popular cartoon double act, they were also the brains behind a raft of favourite TV characters, among them Scooby-Doo, Yogi Bear and The Flintstones. At the height of their success, they were making 11 half-hour shows a week.

Hanna was born in New Mexico but spent his childhood on the move, as his father was a superintendent of construction for the Santa Fe railway. He stumbled into animation after giving up his job as a structural engineer. His first job in the cartoon business was painting cells and punching animation paper for Harman-Ising, the studio which produced Looney Tunes and Merrie Melodies. There, Hanna's talent for writing - not just stories, but music and lyrics - and his natural gift for creating gags emerged.

Hanna and Barbera met in MGM's newly created cartoon department in 1937. Their first collaboration, Puss Gets the Boot, was based around the antics of the characters that evolved into the Tom and Jerry everyone knows. Although they looked slightly different and weren't called Tom and Jerry, the cat and mouse's character traits - dopey cat and wily mouse - and the cartoon's storyline - cat stalks mouse, mouse outwits cat - became the template for each of the 116 Tom and Jerry cartoons that followed over the next 17 years.

Puss Gets the Boot was released in 1940, but it was only after it was nominated for an Oscar that it began to attract attention. Hanna and Barbera set to work on more Tom and Jerry cartoons, always working in the same way, with Hanna concentrating on coming up with (and acting out) ever more inventive gags, and working out the comic timing, and Barbera, the better cartoonist, focusing on the drawings. The cartoons became phenomenally popular, and won seven Oscars for MGM.

Quite suddenly, in the late 1950s, MGM, which was suffering from the damaging effects of television, shut down cartoon production, its rationale being that if it merely reissued the old Tom and Jerry cartoons on a regular basis, it would make almost as much money as it would from new cartoons - and it would save on production costs.

Hanna and Barbera were devastated. Luckily, Columbia Studio's TV arm was planning to broadcast packages of old theatrical cartoons, and it needed new cartoons to function as ''bookends'' for each show. The partners had just come up with a cat and dog team and the concept of The Ruff and Reddy Show was born.

Hanna-Barbera - as they were now known - had to develop a new system of animation which required fewer drawings. Their streamlined system - with condensed storyboards, fewer drawings and use of photocopying - sped up production and became standard for other television animators. Ruff and Reddy hit TV screens in 1957, and its success inspired more characters and more shows. The Huckleberry Hound Show (1958), was the first cartoon series entirely created by Hanna-Barbera: in addition to the adventures of the eponymous drawling dog, each half-hour show featured segments with the mice, Pixie and Dixie, and the inimitable Yogi Bear, who proved so popular that he soon had his own programme. Legend has it that one San Francisco bar had a sign which said: ''No tinkling of glasses or noise during The Huckleberry Hound Show.''

In 1960, Hanna-Barbera were invited to create a situation comedy with cartoon characters. Inspired by the TV sitcom, The Honeymooners, they came up with The Flintstones which was the longest-running cartoon in TV history. It was a new departure for the team, not only because it followed the conventions of a sitcom but also because it featured human characters. Much of the humour lay in the brilliantly clever details of the Flintstones' way of life in prehistoric suburbia. Hanna-Barbera also came up with many new cartoon creations. Top Cat, Touche Turtle, Magilla Gorilla, Atom Ant, and Secret Squirrel are just some of the characters who appeared for the first time in the early 1960s. The Jetsons, a short-lived futuristic variation on The Flintstones, made its debut in 1962 and, while it never had the widespread popularity of its prehistoric counterpart, it has enjoyed a cult following.

In the late 1960s, Hanna-Barbera added yet more strings to their bow by branching out into new types of cartoon: they translated literary classics, Marvel comics, and old live-action comedy shorts into cartoon form, they created spin-off shows from their own series, and launched cartoon versions of existing hit live-action shows.

They even continued to come up with new characters, one of the most successful being Scooby Doo, the quivering canine whose gang of friends travelled the country solving mysteries. Scooby Doo was on television, in various forms, for more than 20 years from 1969. Hanna-Barbera were also adept at picking up on trends, such as the vogue for kung fu films which inspired the Hong Kong Phooey series of the mid-1970s.

It was only in the 1980s, when Hanna and Barbera took a back seat, that the quality of the cartoons began to suffer. Last year the Cartoon Network launched the Boomerang Network, a showcase for the Hanna-Barbera library.

Betty Cohen, the president of the Cartoon Network, said of Hanna, who is survived by his wife, two children and seven grandchildren, ''he was a cartoon scientist and a genius at timing''.

William Hanna, animator; born July 14, 1910, died March 22, 2001.

Alison Kerr