St. Patrick's Day 2018: Reese Witherspoon, Mark Hamill and Kate Walsh celebrate

Irish-American celebrities are spending Saturday celebrating St. Patricks Day.

From encouraging their fans to wear green, or by simply indulging in Irish heritage traditions, celebs are getting in on the holiday fun.

Irish rock band U2 wrote on Twitter that it's a "great day to be Irish," while daytime talk show host Ellen DeGeneres told her fans on the social media network, "Top o' morning to you! I hope everyone has a lucky day."

Here's who else we spotted indulging in the green-loving holiday: