Harmon Rabb Junior was a long-time JAG officer and a Navy Commander who defended and prosecuted various Marine and Naval officers accused of committing any kind of crimes from drug smuggling to murder.
As a result of his father getting involved with a Russian woman whom his father also died protecting after Harm Sr was shot down while flying over North Vietnam on Christmas Eve 1969, Harm has a half-brother named Sergei Zhukov who like Harm later fell under investigation for the death of Lieutenant Loren Singer and both siblings were suspected of fathering the baby Singer had been pregnant with when she'd died.
Leroy Jethro Gibbs even initially thought that Rabb was the culprit and as such, Rabb was arrested and brought to the brig but Special Agent Anthony DiNozzo was successful in proving Rabb's innocence while bringing Lt. Singer's real murderer to justice.
During a talk with Vivian Blackadder, Gibbs admitted that Rabb was the best defender and prosecutor that JAG had which implies that Rabb is one of the most skilled lawyers the JAG team has, his skills even surpassing those of Sarah "Mac" MacKenzie and Bud Roberts Jr.
- David James Elliot who plays Rabb originally hails from Canada and in real life, is married to Nanci Chambers who played Lt. Loren Singer.