Conservatives Lash Out at Actor Bradley Cooper for Appearance at Democratic National Convention

Critics registered their displeasure on Twitter.

Cooper earned critical acclaim and an Oscar nomination for his turn in the 2014 hit film about Chris Kyle, a former Navy SEAL who was killed at a Texas gun range in 2013, allegedly by a former U.S. Marine he was trying to help.

Fans of Cooper's portrayal of Kyle took to Twitter to register their extreme displeasure at seeing the 41-year-old actor at the event on Wednesday night.

Some even called for a boycott of Bradley, while others on Twitter pointed out that playing a character in a movie didn’t require the actor to actually share the character’s views.

The actor did not immediately reply to ABC News' request for comment.