In the early days of Nazi power there was a larger rival group to the SS. However Himmler was against this group, and eventually convinced Hitler eye were rivals to his power. The leaders of this group were shot and executed. The SS was entwined with the police.
With free reign the SS became more deadly and dangerous. The had their own cathedral for planning and religious rites. They had their own ideas in which the German people were to be worshipped instead of God. Himmler took over a castle, Wewelsberg, where his concepts of racial purity could be taught. This would include elimination of "sub humans." They believed in sterilization and execution of those unfit, and polygamy to propagate the race. One goal was to eliminate Christianity.
The SS recruited elite soldiers. Requirements including no glasses and be five feet eleven. SS units were some of they best. They were also involved in spying, local affairs, concentration camps, removal and relocation of people, including Jews, homosexuals and other undesirables.
A strange aspect of SS was a construction project. Project Reise or Giant was seven underground structures connected by tunnels. Their exact purpose is not known, but likely underground factories. They were not finished. However they have many self defense features, such as a grenade chute and gun windows.
In the end Himmler was captured, and killed himself while being interrogated. Many other SS members were tried and executed.