Clyde Harlaown was Lindy Harlaown's husband and Chrono's father, first mentioned in A's. He was an Admiral of the Time-Space Administration Bureau who sacrificed his life to stop the Book of Darkness during the Incident of 0054.

Like in A's, Clyde only makes a posthumous appearance in The MOVIE 2nd A's.

(Source: Nanoha Wikia)