Twitter Inc. has hired ad-agency executive God-is Rivera as global director of culture and community, a new post created to help engage, spotlight and market to informal user groups.

Twitter said Ms. Rivera will help advertisers connect effectively with various communities on the platform driving influential conversations under banners such as Feminist Twitter, Asian-American Twitter, Black Twitter and NBA Twitter. She also will amplify their voices in Twitter’s own marketing, events, company culture and products.

Failure to understand these constituencies can lead to “huge missteps,” Ms. Rivera said. Marketers too often “miss the mark completely on these large groups.” Ms. Rivera previously was director of inclusion and cultural resonance at WPP PLC’s VMLY&R.

“The purpose of this role is to sit at the intersection of marketing, communications and culture,” said Leslie Berland, chief marketing officer and head of people at Twitter.

Marketers have shown interest in social-media communities, but recognize that reactions can be vocal and quite visible. “Part of what we try to do is to make sure that any content that we develop is grounded in real-life insights from the people we serve,” said Damon Jones, vice president of global communications and advocacy at Procter & Gamble Co.

Some brands fear making a misstep that may alienate them from others when they seek specific groups in places such as Twitter or Reddit, said Joselle Galis, senior vice president and head of strategy at Reprise, part of the Mediabrands division of Interpublic Group.

Newsletter Sign-up CMO Today CMO Today delivers the most important news of the day for media and marketing professionals. PREVIEW

“Whether it’s a given group of women, whether it’s an interest people are rallying around like gaming or the NBA, whether it’s Latinas or Black Twitter, the truth is they’ve created these very rich, pure spaces,” Ms. Galis said. “So I think it’s the right move for a brand to be really strategic and thoughtful about the right way to create a relationship with these communities, vs. targeting them as they would as a touch point in any other marketing plan.”

AT&T Inc.’s HBO last summer worked with Twitter and @Blackbirds, Twitter’s business resource group for black employees, to promote “Insecure,” including a video question and answer session with the show’s creator and star, Issa Rae. Earlier this year, Walt Disney Co. ’s Marvel Studios used paid and unpaid posts to market “Black Panther” to several demographics, including black consumers.

Twitter also recently increased its attention on Hispanic users and advertisers that want to reach them, naming Marco Botero, head of Twitter Miami, to the additional, newly created role of head of U.S. Hispanic.

Write to Nat Ives at Nat.Ives@wsj.com