He was bigger than Krazy. He was bigger than Felix. He was bigger than Puss 'n Boots.

But he has stuck his little kitty-cat nose up for the last time. The longest-running finicky act in television history is over.

Morris mortuus est; Morris is dead.

The nationally famous cat, who starred in 40 commercials for Nine Lives Cat Food over the past 10 years, keeled over at his veterinarian's office in Chicago Friday and died, a spokesman said yesterday of "cardiac complications related to old age."

Morris was believed to be 17 but his exact age was never known because he was plucked from the shadow of the gas chamber at a Chicago animal shelter in 1966 and turned into a star.

Bob Martwick, who discovered Morris and remained his trainer after selling him to Nine Lives as the company's official spokescat, could not be reached for comment yesterday. But Pam Talbot, to whom all inquiries regarding Morris were referred by the Nine Lives Company and its ad agency, Leo Burnett, said of Martwick, "He's probably taking it personally."

They were very close.

Talbot, who works for a public relations firm retained to handle Morris's affairs, expressed amazement yesterday at the extent of interest in the fallen star. She had heard from every major news organization, including all three TV networks and all the wire services, and found the response truly incredible."

"The oddest thing," Talbot says, "is that people have been calling and asking where to send flowers. We just tell them to make a contribution to the American Humane Society."

Morris would have liked that.

At the Stuart Kennels in suburban Lombard, where Morris resided throughout his show business career, a casket manufacturer telephoned offering to donate a tiny coffin for the stricken tabby. But Morris had already been buried over the weekend near his trainer's home. There was no ceremony. Morris would have liked that, too.

However, it was by appearing not to like anything - except Nine Lives Cat Food - that Morris became a household pet in millions of American homes.

Aloof, urbane, acerbic and wry in his screen appearances, Morris was, behind the scenes, a quiet, shy and private sort of cat, survivors say. "He was a personal friend of mine," Talbot recalled, "and I would have to say he was definitely a special cat. He was finicky just as portrayed, but he was also very friendly. He was a cat with charisma, there's no doubt about it."

Temperamental? Not Morris. "He was independent, though," Talbot said. "When he felt like taking a rest, he took a rest." That, of course, meant that the director, the sound man, the camera man, the lighting man, and all the other members of the production crew took rests, too. When Morris was through taking a rest, filming would resume.

Morris traveled in limousines, stayed in luxury hotels and flew in an unmarked cage - lest he be mobbed, his trainer used to point out, by adoring fans. Yet he retained the common touch he may have learned in the alleys of his youth and never appeared spoiled by stardom.

When he visited the offices of The Washington Post in 1973, he sat patiently on a desk while staff members stood in line for the opportunity to pet him. And these were hardened journalists who'd managed to keep their cool even when Robert Redford was on the premises making a movie. Actually, Morris and Redford had almost the same color of hair - a kind of goldish orange.

Morris completed filming a few more commercials before his death, but Talbot said all Morris commercials will be pulled off the air "briefly" in memoriam. The memoriam won't last forever, because big advertising dollars are involved.

Thus it is that a replacement for Morris has already been found and is waiting to face the cameras. "I haven't met him," Talbot said. "In fact, I don't even know where he is at the moment, but we do have a successor and he was found in the same way Morris was. He will be called 'Morris'. We don't think viewers will notice the difference."

Morris might not have liked that.

The same actor who did Morris's voice and said all those finicky things will do the voice for the new Morris, but Talbot would not reveal his name. "It's a secret," she said. "Like Santa Claus."

In addition to his commercial work, Morris costarred with Burt Reynolds in the 1973 movie "Shamus." He played the part of a cat.

Throughout the country yesterday fans of Morris reacted to the news of his passing each in his own way.In Long Beach, Calif., a little girl may have spoken for them all when she shouted, "Oh, no!" and then, scooping up her own fat orange cat in her arms, cried out, "I don't want to lose my kitty."