Mark Harmon Returning to NCIS: Origins 4 Years After Franchise Exit

'NCIS: Origins' Crossover Event With 'NCIS': Mark Harmon to Return as Leroy Jethro Gibbs - Episode Date & Details!

‘NCIS’ Star Mark Harmon to Return as Gibbs in ‘NCIS: Origins’ During Veterans Day Crossover

‘NCIS: Origins’ To Feature Guest Appearance By Mark Harmon During Crossover Event With ‘NCIS’