Bosun is a male Tau'ri and First Mate of the Achilles.
When Colonel Cameron Mitchell traveled back in time to restore the timeline and stowed away on the Achilles, Bosun helped him kill Ba'al and his Jaffa. (SG1: "Continuum")
In an Alternate timeline, Ba'al gated aboard the Achilles and he was killed in the Unstable vortex of the Stargate. (SG1: "Continuum")