The bowl-shaped haircut worn by the white supremacist who killed nine black worshipers in Charleston, S.C., stands among the most disturbing and distinctive images that extremists have shared online. Others include letters drawn from the ancient runic alphabet — a particular favorite among neo-Nazis — or slogans like “Diversity=White genocide.”

They are among the many symbols, slogans and memes that white supremacists are deploying as propaganda and which are drawing more scrutiny amid a broader effort to curtail extremist violence in the United States.

On Thursday, the Anti-Defamation League is adding 36 entries to its longstanding online catalog of extremist symbols, many of which are built around racist stereotypes that have been spread about African Americans and Jews.

About 10 of them are the logos of extremist organizations. Several others are numeric codes that can carry hidden messages, like the numbers 109 or 110, anti-Semitic shorthand that claims that Jews have been expelled from 109 countries and that the United States should become the 110th.