Journalists on postage stamps

This week the U.S. will preview five stamps featuring 20th Century journalists.

A press notice of an Oct. 5 press conference names them:  war correspondent Martha Gellhorn (1908-1998); John Hersey (1914-1993), whose most famous work, was Hiroshima;  CBS correspondent George Polk (1913-1948), killed while reporting on corruption involving U.S. aid in Greece after WW II; Ruben Salazar (1928-1970), the first Mexican-American major mainstream media journalist, who was was shot and killed by
a deputy sheriff while reporting on a Vietnam War protest; and WW II correspondent Eric Sevareid (1912-1992).

From the press note:
The U.S. Postal Service honors five journalists who reported — often at great personal sacrifice — some of the most important events of the 20th century. Working in radio, television or print, these distinguished journalists filed stories from domestic and international hot spots. Their description of conflicts and issues helped Americans respond more intelligently to events. The stamps will be issued in 2008.

Who ought to be on Canadian stamps?