Theodore Horstmann is an orchid expert who assists Wolfe in the plant rooms. His living quarters are adjacent to the plant rooms on the brownstone's top floor. In the first Wolfe book, Fer-de-Lance, Archie remarks that he sometimes hears "old Horstmann" yelling at Wolfe, who "seemed to have the same effect on Horstmann that an umpire had on John J. McGraw," though he is sure that Theodore doesn't dislike Wolfe.
The Horstmann character is often little more than a plot device — as in Door to Death in which his extended absence forces Wolfe to find another orchid tender. But in Black Orchids, Theodore's actions are central to the denouement; and in chapter five of The Second Confession Theodore's welfare is of great concern to Wolfe.
In spite of the great emphasis on food and eating throughout the series, little mention is made of where, when, or what Horstmann eats, except that in Plot It Yourself he is said to eat in the kitchen with Fritz. Theodore has a sister in New Jersey and sometimes spends time there.
Saul Panzer is a top-notch private detective who is frequently hired by Wolfe either to assist Archie or to carry out assignments Wolfe prefers that Archie not know about. Panzer is not an impressive looking character; he dresses sloppily, has a big nose, and almost always needs a shave. Even so, Archie and Wolfe respect Saul immensely. He charges much higher fees than other New York detectives, but Archie insists he's worth every cent.
Saul occupies different residences in the Wolfe corpus. In The Next Witness, he has an apartment in Manhattan to himself. Its main room has four lamps, a grand piano, a wall with windows, another wall solid with books, and ". . . the other two had pictures and shelves that were cluttered with everything from chunks of minerals to walrus tusks."
The role of Saul Panzer is played by George Wyner in the NBC TV series Nero Wolfe (1981). Saul Rubinek played the role in the A&E original film The Golden Spiders: A Nero Wolfe Mystery (2000). In the A&E TV series A Nero Wolfe Mystery (2001–2002), Conrad Dunn is Saul Panzer.
Orrie Cather is a handsome, personable detective, someone people want to tell things — but he can be too full of himself. In The Mother Hunt (chapter 9), after Wolfe leaves it to Saul to teach Orrie better manners, Archie warns Wolfe, "You know, if you pile it on enough to give Orrie an inferiority complex it will be a lulu, and a damn good op will be ruined." But Archie, too, has an occasional run-in with Orrie, who thinks he would look just fine sitting at Archie's desk.
Orrie's talents as a professional operative are much narrower than Archie's. He has neither Saul Panzer's genius for tailing, nor his memory for faces, nor his instinct for the best move. And while he's brighter than Fred Durkin, Orrie exhibits little of Fred's bulldog tenacity. But he is handsome, and Stout furnishes him more complex motives than he does Saul or Fred. Ambiguities in Orrie's character are introduced as early as The League of Frightened Men (1935); and by Death of a Doxy in 1966, Wolfe states, "You must know that I have no affection for him.
Orrie's full first name is one of the inconsistencies in the corpus. In chapter 16 of The Golden Spiders (1953), clothing store owner Bernard Levine states that he was shown "a New York detective license with his picture on it and his name, Orvald Cather." In chapter 3 of If Death Ever Slept, Archie calls the office and Orrie answers the phone, "Nero Wolfe's residence. Orville Cather speaking." And, thinking he was clarifying the matter, Rex Stout's biographer John McAleer asked the author, "Is Orrie Cather's given name Orrin?" "Probably," Stout replied.
Cramer has enjoyed twitting Wolfe by rising from the red leather chair without using his arms for leverage – something that Wolfe cannot do.
Cramer has considerable respect for Wolfe's investigative skill. In The Doorbell Rang, Cramer goes to some lengths to keep the state of New York from taking Wolfe's and Archie's licenses as private investigators. And in In the Best Families, Cramer says, "Wolfe is too cocky to live ... I would love to bloody his nose for him. I've tried to often enough, and someday I will and enjoy it. But I would hate to see him break his neck on a deal like this where he hasn't got a chance. Cramer is also grateful to Wolfe for saving his job in The Silent Speaker. Near the end of that book, Cramer expresses his gratitude by bringing Wolfe " ... a misshapen object covered with green florist's paper" that turns out to be an orchid.
Cramer shares few, if any, of Wolfe's tastes; in the story "Black Orchids", for example, Wolfe exclaims that the black orchids are unique, matchless and incomparable, Cramer replies that "They're pretty ... Kind of drab, though. Not much color. I like geraniums better.
Cramer is a cigar chewer. In early Nero Wolfe novels, Cramer lights and smokes them, but in later novels Archie notes that Cramer only chews on cigars and has never been known to light one. Cramer often ends his visits to Wolfe's office by angrily throwing his chewed cigar at the wastebasket, usually missing the target. Archie suspects that the cigars give Cramer a moment to calm down before he says something regrettable.
Cramer is married and has one son, who fought in the Australian theater during World War II.
Cramer's first name, Fergus, is given once only, in 1940's Where There's a Will. However, his initials are later given as "L.T.C." in 1946's The Silent Speaker, due to Stout's failure to recall that he had earlier given Cramer a first name. This led to Robert Goldsborough giving him the full name of "Lionel T. Cramer" in Goldsborough's version of Nero Wolfe novels.
"To me he is just Inspector Cramer," Stout said.
Cramer is the protagonist of one Stout novel, Red Threads (1939).
Inspector Cramer was portrayed by Biff McGuire in the 1977 TV movie Nero Wolfe, and by Allan Miller in NBC TV's 1981 series. In the A&E TV series A Nero Wolfe Mystery (2001–2002), the role of Inspector Cramer is played by Bill Smitrovich. Archie hears him called Fergus in the episode The Silent Speaker, when he makes the brief acquaintance of Mrs. Cramer.
Lieutenant George Rowcliff is a police lieutenant for whom Wolfe harbors special animus, partly due to an incident in which Rowcliff took Wolfe into custody. As Wolfe once puts it, "This whole performance is based on an idiotic assumption, which was natural and indeed inevitable, since Mr. Rowcliff is your champion ass – the assumption that Mr. Goodwin and I are both cretins.
Rowcliff is the only character acknowledged by Stout to have been consciously modeled and named after a real-life person — a young naval attache under whom Stout served while a yeoman on Theodore Roosevelt's Presidential Yacht Mayflower in 1906–07 and to whom Stout took an intense and enduring dislike. Whether the connection between the real and fictional Rowcliffs was known contemporaneously, it is clear that the source of Stout’s obnoxious cop suffered no ill effects professionally: Gilbert Jonathan Rowcliff went on to a distinguished naval career spanning both world wars, at sea as an honored commander and in Washington as Judge Advocate General, a position he assumed in June 1936, shortly after his namesake was introduced in The Rubber Band. It is also clear that whether the naval Rowcliff followed Stout’s career or read and recognized himself in the Nero Wolfe books, Stout followed his; in an interview with John McAleer, the author dead-panned, “he retired in December 1945, with the rank of rear admiral.”
The role of Rowcliff is played by Bill MacDonald in the A&E TV series A Nero Wolfe Mystery (2001–2002).
Archie, Lon, and some other Wolfe regulars play poker Thursday nights at Saul Panzer's apartment.
Over the years, Wolfe and the Gazette develop a symbiotic relationship that gives the newspaper exclusive information regarding Wolfe's cases, and that gives Wolfe publicity – sometimes, more than he would want.
Lon's role at the New York Gazette is not further detailed in the Rex Stout stories, but it becomes central to the story line in Robert Goldsborough's novel Death on Deadline.
Lily is one of the few women for whom Nero Wolfe has a grudging respect: "I have not only eaten her bread and salt, I have eaten her grouse. I am in her debt.
Lily's father, who made his money building New York's sewer system, helped Inspector Cramer get started at the NYPD, and this background sometimes causes him a conflict of interest where Lily is concerned.
In Lady Against the Odds, a 1992 TV adaptation of The Hand in the Glove, Dol Bonner is played by Crystal Bernard.
Zeck’s malevolent presence intrudes via telephone in two novels, And Be a Villain (1948) and The Second Confession (1949). Zeck had previously telephoned Wolfe twice, on June 9 1943, concerning Wolfe’s work for General Carpenter, and on January 16 1946, regarding Mrs. Tremont. Zeck himself appears in In the Best Families (1950). In the third book of what is popularly called The Zeck Trilogy, Nero Wolfe resolves to defeat Zeck once and for all. In 1974, the Viking Press collected the three Zeck novels in an omnibus volume, Triple Zeck.
"I was thrilled when Wolfe finally encountered his own Moriarty in the archvillain Arnold Zeck," wrote Michael Dirda, Pulitzer Prize-winning book critic for The Washington Post.British author and literary critic David Langford has also noted that the relationship between Zeck and Wolfe compares to that of Professor Moriarty and Sherlock Holmes.