The Chance Twins/Rich and Jade series by Jack Higgins consists of 4 books, published between 2007 and 2009. The series begins with Sure Fire.
The Dougal Munro and Jack Carter series by Jack Higgins consists of 3 books, published between 1986 and 1998. The series begins with Night of the Fox.
The Liam Devlin series by Jack Higgins consists of 4 books, published between 1975 and 1991. The series begins with The Eagle Has Landed.
The Martin Fallon series by Jack Higgins consists of 2 books, published between 1960 and 1973. The series begins with Cry of the Hunter (As: Harry Patterson).
The Nick Miller series by Jack Higgins consists of 3 books, published between 1965 and 1968. The series begins with The Graveyard Shift.
The Paul Chavasse series by Jack Higgins consists of 6 books, published between 1962 and 1979. The series begins with The Bormann Testament / The Testament of Caspar Schultz.
The Sean Dillon series by Jack Higgins consists of 22 books, published between 1992 and 2016. The series begins with Eye of the Storm / Midnight Man.
The Simon Vaughn series by Jack Higgins consists of 3 books, published between 1967 and 1979. The series begins with Dark Side of the Street.