Professional actress, cat owner, and sometime cat sitter Alice Nestleton is drawn into the world of amateur sleuthing when the first of a string of murders happens to be one of the owners for whom she is cat sitting in Lydia Adamson’s A Cat in the Manger. Part of a series.

Ex-marine and current mystery bookstore owner Penelope Warren and her cat Mycroft aka Big Mike, an Abyssinian alley cat, are quite a team.  Drawn into a case of horse napping and murder, they are bent on seeing that justice wins in the end in Stable Cat by Garrison Allen.  Part of a series.

Jim Qwilleran and Koko were first introduced in The Cat Who Could Read Backwards by Lilian Jackson Braun.  Desperate for any decent newspaper job, Jim becomes the new art critic for the Daily Fluxion.  When he begins to explore the modern art, he discovers vandalized art and murder.  With the help of his landlord’s Siamese cat, Koko, Jim solves the case.  First in a series.

Marian Babson has written many standalone English mysteries featuring cats.  In The Cat Next Door, Margot returns to England to find that her cousin, Chloe is accused of murdering her twin sister Chloe.  With help from the family cat, Margot sets out to find the real murderer.

Rita Mae Brown first wrote about Mrs. Murphy, Tucker, and small town Virginia postmistress Mary Minor “Harry” Haristeen in Wish You Were Here.  Harry and her animals become involved in a series of gruesome and bizarre murders that several bizarre and gruesome murders that are preceded by the arrival of a "wish-you-were-here" postcard picturing a gravestone in a cemetery.  First in a series.

Working on publicity for a strippers’ convention in Las Vegas after the first publicist dies from a heart attack when he finds one of the strippers murdered, Temple Barr and her cat Midnight Louie are caught up in a series of murders of the strippers in Pussyfoot by Carole Nelson Douglas.  Part of a series.

Evan Marshall’s Missing Marlene introduces widowed mother and literary agent Jane Stuart and her cat Winky.  When nanny Marlene disappears, Jane and Winky must go to the wrong side of town to try and track her down.  First in a series.

Shirley Rosseu Murphy’s feline P.I. Joe Grey is some cat—he talks, understands humans, and knows how to read.  When he finds himself behind the alley of Jolly’s Deli he becomes the only witness to a murder in and must try to escape being killed in Cat on the Edge.  First in a series.