Domenick Lombardozzi (Photo: Getty Images)

HBO veteran Domenick Lombardozzi is joining the cast of “Boardwalk Empire” for the gangster drama’s fourth season, Deadline.com reportshere.

Lombardozzi, 36, will play Ralph Capone, older brother of Chicago mob kingpin Al Capone (played by Stephen Graham) — a character not previously seen (or, in our memory, mentioned) in the Steve Buscemi series’ first three seasons.

Yes, there was a real Ralph Capone. We’ll save you a trip to Wikipedia: Ralph Capone, nicknamed “Bottles,” was once known as the FBI-designated “Public Enemy No. 3″ (his brother Al was No. 1 at the time).

Incredibly, Ralph Capone lived until 1974, when he died of natural causes at age 80.

The Deadline story doesn’t give any indication of the importance of Ralph Capone to the ongoing storyline in “Boardwalk Empire,” nor does it say whether Lombardozzi is in for the whole season or just part of it.

Lombardozzi was last seen on the A&E series “Breakout Kings,” where he played the leader of an elite law enforcement team partially made up of ex-cons whose job was to capture prison escapees.

But he has popped up repeatedly on HBO, starting with a recurring role in “Oz,” then a starring a role in “The Wire,” then recurring or guest-starring roles on “Entourage” and “Bored to Death.”

The new season of “Boardwalk Empire” is expected to premiere next September.