Peacemonger

[Little_Girl]

1.) The opposite of a [warmonger]...[not necessarily] a bad term...
2.) anyone other than [George W. Bush]

[Oralee]

A person who encourages or advocates peaceful conduct towards other nations or groups.

[Dave Paprocki]

1.) Someone that will attain political/social peace through excessive nonviolent means, usually at the expense of [national security] and respect.
2.) Someone who naively uses the phrase [peace in] [our time]