In composer John Adams’s last world-premiere opera, he brought to life a character snatched from the history books. Now, tenor Paul Appleby returns — to give voice to another power-hungry figure from the past. In John Adams’s new opera “Antony and Cleopatra,” Appleby plays Caesar, a firebrand who chafes under the communal leadership of the Roman Republic. He longs to be the sole ruler — to usher in a period of empire under his name. Appleby is no stranger to the San Francisco Opera stage — nor to John Adams’s work. In 2017, he originated the role of Joe Cannon in the opera “Girls of the Golden West,” which chronicled the violences of the California Gold Rush. Joe Cannon was more than a character, though. He was a real-life figure — someone who helped spark a horrific act of violence. The evening of July 4, 1851, Cannon, a miner, was stumbling drunk down the main street of Downieville, California, when he illegally entered the home of a Mexican-American woman named Josefa Segovia. What happened next is unclear: Some speculate he might have assaulted Segovia in her home. When he returned the next day — whether to apologize or to continue his harassment — Segovia stabbed him to death. Vengeful miners then formed a lynch mob to arrest and hang her, in what would be one of the most enduring incidents of anti-Mexican violence in California history. Cannon was a harrowing, menacing role for Appleby to play — and he returns with even more menace for his new role in “Antony and Cleopatra.” See him on stage once more this September: sfopera.com/cleopatra (📸: Cory Weaver and Stefan Cohen)