Claim: William Shatner portrayed a police sergeant.

William Shatner -LRB- born March 22 , 1931 -RRB- is a Canadian actor , author , producer , and director . In his seven decades of television , Shatner became a cultural icon for his portrayal of James T. Kirk , Captain of the USS Enterprise , in the Star Trek franchise . He has written a series of books chronicling his experiences playing Captain Kirk and being a part of Star Trek , and has co-written several novels set in the Star Trek universe . He has written a series of science fiction novels called TekWar , which were adapted for television .   Shatner also played the eponymous veteran police sergeant in T. J. Hooker -LRB- 1982 -- 86 -RRB- and hosted the reality-based television series , Rescue 911 -LRB- 1989 -- 96 -RRB- , which won a People 's Choice Award for the Favorite New TV Dramatic Series . Shatner also appeared in the NBC series , 3rd Rock from the Sun in seasons 4 and 5 as the role of the `` Big Giant Head '' whom the alien characters of the Series reported to . From 2004 until 2008 , he starred as attorney Denny Crane in the final season of the legal drama The Practice and its spinoff series Boston Legal '' , a role that earned him two Emmy Awards .   Shatner has also worked as a musician , an author , a director , and a celebrity pitchman .