Which CEO co-founded Twitter and served as CEO again in 2015?

Jack Dorsey is the Twitter co-founder who served as its CEO again in 2015.

Dorsey helped create Twitter after the Odeo team developed the short-message service that became a separate company. He was Twitter’s first CEO, leading the company from 2007 until 2008, when Evan Williams replaced him. Dorsey remained involved as chairman and returned to the chief executive role after Dick Costolo resigned in 2015.

He first became interim CEO in July 2015 and was appointed permanent CEO in October of that year. His second tenure lasted until 2021, when Parag Agrawal succeeded him. Dorsey was therefore both Twitter’s founding-era CEO and the executive who guided it during its later public-company period.

A common mix-up is confusing Dorsey with Evan Williams or Biz Stone, who also played central roles in Twitter’s creation and growth. Mark Zuckerberg founded Facebook, not Twitter. Dorsey also co-founded Square, later renamed Block, a separate financial-technology company.