1) Creator 2) Founder 3) Maker 4) Producer 1) First-move maker 2) Instigator 3) Leader 4) One starting something 5) Person getting things started 6) Spark provider 
• (n.) One who initiates.
a source of any chemical species that reacts with a monomer (single molecule that can form chemical bonds) to form an intermediate compound capable ...
A unit that receives electrical or detonation energy and produces a chemical deflagration reaction.
A compound required to start a chain reaction, such as free-radical polymerisation. Unlike a catalyst, it is consumed in the reaction, but only a small quantity is normally required since one molecule of initiator can initiate the reaction of many other molecules. 
An agent which starts the process of tumour formation, usually by action on the genetic material.Any agent which starts the process of tumour formation, usually by action on the genetic material, is called an initiator.
A substance that is used to start a chemical reaction
a SCSI device that requests another SCSI device (a target) to perform an operation; usually a host computer acts as an initiator and a peripheral device acts as a target. 
In·i'ti·a`tor noun [ Latin ] One who initiates. 
A compound required to start a chain reaction. Unlike a catalyst, it is consumed in the reaction, but only a small quantity is normally required.