A Marlboro billboard1 in Denver in an undated photo.

They influence everything from how we look and act to eat and speak and have even helped sway the course of history - but they are not real.

And topping a list of "The 101 most influential² people who never lived" in a book released on Tuesday is the Marlboro Man - a macho American cowboy who emerged in the 1950s and helped boost sales of Marlboro cigarettes.

"The figments of our imaginations, the creatures we push out of our minds into the real world are fully³ capable of pushing back with surprising consequences," Jeremy Salter, one of the US book's three authors said.

Coming in at number two on the list is Big Brother of George Orwell's 1984, followed by King Arthur , who the authors say embodies⁴ for many the ideal monarch⁵, and Santa Claus comes in at number four.

"Santa Claus governs our entire economy for the last quarter of the year and without him businesses would go broke," said co-author Allan Lazar.

Barbie "the bodacious plastic babe who became a role model for millions of little girls, setting an impossible standard for beauty and style" makes the list at number 43.

"The idea came to us that influential characters didn't have to exist, that fictional⁶ characters were just as important in our lives, even in maybe some cases more so than real people," Lazar said.

Even the Loch Ness Monster makes the list at number 56.

"As the most popular tourist attraction in Scotland, Nessie's influence on the cash flow of that country has been significant," wrote the authors of "The 101 most influential people who never lived."