Summary

• Miles O'Brien's unique Chief Petty Officer rank in Star Trek made him a fan favorite character due to his relatable everyman persona.
• O'Brien's rank history was inconsistent in the early days of Star Trek: The Next Generation, finally confirmed as Chief in the episode "Family."
• Chief O'Brien's non-commissioned status provided a different perspective on Starfleet, showing his seniority and experience in his role.

Chief Miles O'Brien (Colm Meaney) has a fairly unique Starfleet rank, being Colm Meaney's acting in the role, but also due to O'Brien's non-commissioned status, meaning that, as Chief Petty Officer, he enlisted as a civilian, and didn't come up through Starfleet Academy.

While Miles O'Brien is known as the "Chief", the character had a slightly inconsistent rank history during the early days of Star Trek: The Next Generation. Various early episodes of TNG have O'Brien wearing an ensign's pip or referred to as lieutenant. It wasn't until the episode "Family" that TNG finally confirmed O'Brien's rank as a Starfleet officer. "Family" writer Ronald D. Moore explained why he decided to make O'Brien a Chief Petty Officer in a 1998 AOL chat:

"He officially became a Chief Petty Officer in "Family" when I wanted he and Worf's adoptive father to both be non-coms in contrast to Worf. Making him an enlisted man seemed to give us another color in the show and to open up another window into Starfleet that we hadn't explored before."

Chief O’Brien’s Starfleet Rank Explained

As confirmed in Star Trek: The Next Generation season 4, episode 2, "Family", Miles O'Brien is a Chief Petty Officer. Like Starfleet's other ranks, the Chief Petty Officer has its origins in the United States Navy. In both the Navy and Starfleet, a Chief Petty Officer is one of the most senior non-commissioned officers, and promotion to the role is based on things like performance, time in service, and exceptional evaluation scores. For that reason, Chief Petty Officers generally have a lot more hands-on experience than Lieutenants and Ensigns, giving them a degree of seniority and responsibility.

Chief O'Brien shares something in common with Star Trek: The Original Series' Janice Rand (Grace Lee Whitney) as she was the Enterprise's transporter chief in Star Trek: The Motion Picture.

Miles O'Brien's years of experience as O is why he was selected to become Deep Space Nine's Chief of Operations. Chief O'Brien had a bigger role as a Star Trek: Deep Space Nine character than he did in Star Trek: The Next Generation. Indeed, O'Brien's move to DS9 represented a promotion from Chief Petty Officer to Senior Chief Petty Officer, the second-highest non-commissioned rank after Master Chief of Operations. As a perk of his non-commissioned status, O'Brien was also able to skip boring formal dinners like the one he hoped to miss in DS9 season 3, episode 11, "Past Tense, Part I".

Surprising Star Trek Officers Who Outrank DS9's Chief O’Brien

Due to the differences between commissioned and non-commissioned Starfleet officers, Chief O'Brien is outranked by some surprising Star Trek characters. In Star Trek: Deep Space Nine season 3, episode 25, "Facets", O'Brien muses that, should Nog (Aron Eisenberg) graduate from Starfleet Academy, then the young Ferengi officer will outrank him. While that was technically true, Nog always showed due deference to O'Brien, referring to him as "Sir" throughout DS9. Nog's reverence for O'Brien is understandable, given his positive impact on the professional life of Nog's father, Rom (Max Grodenchik).

Even before they were all promoted to Lieutenant Junior Grade in Star Trek: Lower Decks season 4, Beckett Mariner (Tawny Newsome) and Brad Boimler (Jack Quaid) would have outranked O'Brien when they were Ensigns. However, the reverence shown to Chief O'Brien's dart board in Lower Decks' crossover with Star Trek: Deep Space Nine proves that they too would also respect Miles' knowledge and experience. After all, it's also Lower Decks that jokingly stated that Chief O'Brien was the most important man in the history of Star Trek. Not bad for a non-commissioned officer.

All episodes of Star Trek: Deep Space Nine are available to stream on Paramount+.