KANSAS CITY, Missouri (AP) -- Calvin and Hobbes, the terrible tyke and his sidekick tiger, will be retired from the funny pages on December 31.

In a letter to newspaper editors Thursday, cartoonist Bill Watterson said the decision to end the strip was not a recent or easy decision.

"I believe I've done what I can do within the constraints of daily deadlines and small panels," Watterson, 38, said in the letter. "I am eager to work at a more thoughtful pace, with fewer artistic compromises."

"Calvin and Hobbes" hit the comic pages in 1986 and entertained millions with the antics a 6-year-old boy with an overactive imagination and a not-so-stuffed tiger.

In the past nine years, the pair launched countless snowball ambushes, journeyed through space, tormented a baby sitter and ran afoul of Calvin's patient parents.

"Calvin and Hobbes" is distributed internationally to nearly 2,400 newspapers. More than 23 million copies of books based on the cartoon are in print. All 13 collections were million- dollar sellers in their first year.

In his letter, Watterson said he had not decided on what he will do next.

Lee Salem, editorial director at the Universal Press Syndicate in Kansas City, said that after December 31, the company will not provide reruns of the strip to newspapers the way it did when Watterson took a nine-month leave of absence in 1991 and again last year.

Salem said two "Calvin and Hobbes" book collections will be released next year. The books include comic strips that have already appeared in newspapers.

Beyond that, Salem said Universal Press does not know if Watterson will produce new books or other materials.

"We hope he'll come up with something we can use in the market," Salem said, "but we don't know what the market will be."

The reclusive cartoonist has refused to be interviewed and will not reveal where he lives.

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