The Captain is the Captain of their ship. And only their ship. Sometimes.
In my post The most important role for quality is the Product Owner (?!), it was rightly mentioned in the comments that
Product Owner is a particular role in the Scrum methodology, which does not exist similarly for XP, Lean or Crystal in this particular sense
But the spirit and intent of the Product Owner is what I was trying to channel. In any methodology there is someone who could have a plaque on their desk with the word ‘the buck stops here’ embossed on it. So how you do determine who that person is if they don’t have the acknowledged title of Product Owner?
Let’s call this the Ship’s Captain heuristic.
A Captain is master of the ship. His (or her) word is law and is not to be questioned. If they tell the engine room ‘all ahead full’ then that is the engine speed. Likewise if they say that all meals will be designed for herbivores then it is ‘no meat for you’.
In this analogy the Captain is the Product Owner, the engine room folk are the developer and the people running the kitchen are testers. Everyone has a role to play on board and is critical to the success of the mission. (Just try to operate a ship without means of propulsion or food for any length of time.) Each also has their own set of objectives and ways of achieving them, but ultimately, they take their lead from the Captain.
And the ship is of course the product in all this.
This isn’t to say that the Captain is always omnipotent in their ability to provide instructions. In a fleet context, the Captain takes order from the Admiral, and they in turn get them from Fleet Headquarters. But in a owner-operator/privateer perspective they really do make all the rules.
Truly effective Captains also take into account the opinions of their crew when making decisions. But sometimes, they do have to make the unpleasant choice for the overall betterment of the mission.
So who is the Captain of your ship? They are the ones who, barring outside intervention, really control the Quality of the product.