Depends on the context for Imams.. Shia have them as the second in command to the prophet himself, Sunnis have them just as the prayer leader in their mosque.. I think in Shia, most of them were killed by poison.. (the major 12) and there are different meanings of the term depending on which denomination of islam. Personally? I think Alwai, Sufi and Wahabi are kinda interesting, but Ahmadiyya is very interesting. They are a Islam denomination which believe Jesus christ was a prophet of Israel who on the cross, didn't die but fainted, and then went to India where he died at the age of 120. They believe Violence of any kind, physical or verbal, is a violation of Islam, though self-defence is allowed.