Don Sparks has played three different characters over the course of the series:
- Episode 18.17 Personae Non Grata (2008) - James Kelvin
- Episode 15.1 Paradigm (2004) - CSU Tech Dill
- Episode 14.10 Ill-Conceived (2003) - CSU Tech Dill
- Episode 11.12 Teenage Wasteland (2001) - ADA Lawrence Donato
Ralph Byers has portrayed four different characters over the course of the series:
- Episode 8.17 Carrier (1998) - Mr. Kiley
- Episode 5.17 Act of God (1995) - Alex Gaston
- Episode 3.21 Manhood (1993) - Neil Belden
- Episode 1.21 Sonata for Solo Organ (1991) - Judge Barsky