Frank Gallo was an inmate incarcerated at Danbury Federal Prison for racketeering. He was investigated for conspiracy to commit murder.
On Mike Ross' first night, Frank posed as Mike's new cellmate and pretended to befriend him, conning him into texting Rachel Zane from his phone. However, it was revealed that Frank was prosecuted by Harvey Specter thirteen years ago and that Frank was attempting to get back at Harvey through Mike.
In "100", he was murdered by Masterson Construction and Reform Corporation to prevent him from testifying against them.