Though Len Cariou originated the role on Broadway, George Hearn starred opposite Angela Lansbury in the national tour of Sweeney Todd: The Demon Barber of Fleet Street (1982). The PBS show "Great Performances" filmed the Broadway production after George took over the lead, so it's his performance opposite Angela that was seen by viewers.
Dakin Matthews (Neal Gillen) appeared in three episodes as different characters (S9.E4, S10.E7, S11.E12). Despite being an American actor, the first two episodes Matthews appeared in were set in Ireland, with him putting on an Irish accent.
Michael Alldredge plays Jason MacNamara. Alldredge was notably Tony Montana's lawyer, George Sheffield, in Scarface (1983). In December 1997, Alldredge died from lung cancer five years after this episode aired. He was 56.
John Finnegan (Douglas Foudy) also appeared in S6.E12 "Good-Bye Charlie" as a different character (Uncle Charlie).