Comic giant DC is facing calls to sack a new Superman comic writer because he believes marriage should be between a man and a woman.
Gay rights activists are angered that Orson Scott Card is a board member for a group that campaigns for traditional marriage.
And he has been compared to a Holocaust denier or a white supremacist for his views, by one critic.
DC has commissioned the sci-fi author Mr Card to write for their digital Superman series.
A petition collated by homosexual lobby group All Out has been signed by more than 10,000 people calling for DC to drop Mr Card because of his views on marriage.
However, a gay comic writer has criticised the attack on Mr Card’s appointment.
Dale Lazarov said: “Asking for workplace discrimination for any reason is counterproductive for those who want to end discrimination on their own behalf.”
But actor Michael Hartney has written to DC complaining about the hiring of Mr Card.
He said: “If this was a Holocaust denier or a white supremacist, there would be no question. Hiring that writer would be an embarrassment to your company.”
And comedian Brett White said Mr Card’s beliefs mean he would be unable to “put himself firmly into Superman’s mindset as a protector of the human race”.
Mr Card joined the board of campaign group National Organization for Marriage in 2009.
DC Comics said: “As content creators we steadfastly support freedom of expression, however the personal views of individuals associated with DC Comics are just that — personal views — and not those of the company itself.”
A number of people have faced disciplinary action by their employers just because of their beliefs about marriage.
In October, a university diversity officer in America was suspended for signing a petition calling for a referendum on the issue of same-sex marriage.
And in the UK, a housing manager was demoted and had his pay slashed because he wrote on his private Facebook wall that gay weddings in Churches was “an equality too far”.