The woman who came up with a neon sign that has welcomed countless visitors to "fabulous Las Vegas" since 1959 has died.

Betty Willis, credited with designing the "Welcome to Fabulous Las Vegas" sign, died in her Overton, Nevada, home on Sunday, according to an obituary on the Virgin Valley & Moapa Valley Mortuaries' website.

The 91-year-old artist's often-copied sign sits in a median in the middle of Las Vegas Boulevard south of the Strip.

"It's the most recognizable icon in the world," said Danielle Kelly, executive director of The Neon Museum in Las Vegas, where the signs of Sin City's past are retired and on display.

The welcome sign's design, which doesn't have a copyright owner, has become a fixture on travel tchotchkes from Vegas and everywhere else, Kelly said. She has a T-shirt from San Francisco with that city's name swapped in for Las Vegas in front of the sign's recognizable shape, she said.

"The fact that everyone loves that sign and its design after all these years is a testament to Betty's talents," Clark County Commissioner Steve Sisolak said. "There is probably no bigger Las Vegas icon than that sign."

In 2009, the sign was added to the National Register of Historic Places.

Kelly called Willis' designs dazzling and said her personality was akin to a strong, fast-talking female lead in movies like "His Girl Friday."

"A little salty, a little irreverent," Kelly said with fondness. "I thought she was a classic broad."

Willis, born in 1923 in the small town of Overton northeast of Las Vegas, worked as a commercial artist in Los Angeles before returning to Las Vegas, where she worked for sign companies and designed the famous diamond-shaped beacon of flashing lights.

The sign has become such a popular photo backdrop that a parking lot for cars and tour buses in the middle of the street was expanded in 2012.

Willis also designed neon signs for the Moulin Rouge casino and Blue Angel motel in Las Vegas.