SALT LAKE CITY — Three past celebrity guests of Salt Lake's popular FanX convention are asking to file briefs in court supporting the organization's argument that the term "comic con" is generic and widely used.

The question is at the center of a yearslong legal battle between FanX and the iconic San Diego Comic-Con International over the Salt Lake event's original name, Salt Lake Comic Con.

In a motion filed Friday afternoon in the 9th Circuit Court of Appeals, actors Zachary Levi, Manu Bennett and Kevin Sorbo joined the heads of two other comic convention companies, as well as a convention consultant and talent manager, in a request to file an amicus brief in the case.

A sample of the "friend of the court" brief argues that if a district court ruling is allowed to stand affirming San Diego Comic-Con's trademark over the widely used term, dozens of other conventions would be forced to either pay financially untenable licensing costs or to cease operation, damaging the convention industry and the celebrities, businesses and guests. The brief also argues the cities and venues that host popular arts conventions would be harmed through lost income.

The group behind the brief also argue they have always understood "comic con" to be a generic term as they "have been producing, attending, and participating in comic conventions in various capacities for approximately a decade, and for some, multiple decades. Not one has ever chosen to attend or participate in a comic convention marketed as a 'comic con' because he or she understood any such convention to be affiliated in some way with San Diego Comic Convention."

A jury in San Diego in December 2017 found that the Salt Lake Comic Con name violated San Diego Comic-Con's trademark, but ordered that the company pay just $20,000 of the $12 million damages San Diego asked for. FanX is appealing the ruling and fighting a judge's order to pay its opponents' legal fees.

A filing in support of the amicus brief argues that because of their experiences either participating in popular arts conventions around the world or running their own, the group is deeply familiar with the industry and directly impacted by the court's decision.

The brief asserts that Levi, star of the upcoming "Shazam!" movie and the TV series "Chuck," who operated his own popular arts convention Nerd HQ, attends an average of five comic conventions each year, including FanX in 2017.

Bennett is a fan favorite at the Salt Lake convention and has appeared in Salt Lake City multiple times and attends between 10 and 20 other conventions each year, according to the brief. He appeared in the Hobbit movie trilogy and the "Arrow" TV series.

Sorbo, known for several TV roles, including his time as the hero in "Hercules: The Legendary Journeys," began attending fan conventions in 1995 and generally appears at 30 each year, according to the brief. Sorbo was a guest in Salt Lake City in 2014.

Others in the brief include Jim Burleson, producer of Albuquerque Comic Con and Santa Fe Comic Con; John D. Maatta, CEO of Wizard Entertainment, Inc., which puts on 10 to 17 events each year; and Julie Caitlin Brown, an industry expert who has consulted with fan events around the world.