"T.H.E. Cat" was indeed about a cat burglar,
full name Thomas Hewitt Edward Cat (!).
"Nichols"/"James Garner As Nichols" lasted only
one season (1971-72). At first, he was a cowardly
sheriff in the Maverick mold; in order to try to save
the show, which was borderline in the ratings, NBC
had the original Nichols killed off and replaced by his
brother (IIRC), a more conventional Western lawman.
That's when the title change was made, but the ratings
didn't improve enough to warrant a renewal, and Garner
had to wait two years for his next big hit: "The Rockford
Files."
"Topper" isn't really so strange a name; he's Cosmo Topper
(Leo G. Carroll), who owns the house once inhabited by
George and Marion Kirby (Robert Sterling and Anne Jeffreys),
now ghosts, and only he can see them.
Likewise "December Bride" refers to a very eligible and
desirable (yes, older men are crazy about her) senior citizen,
Lily Ruskin (Spring Byington), who's always looking for a husband.
Watch for Harry Morgan as neighbor Pete Porter, who later got
a spinoff, "Pete And Gladys."
One I think is a little strange is "Lotsa Luck," with Dom DeLuise
as a bus driver who lives with his family. Since it's based on a
British sitcom, I'm not surprised.