According to legend, their history suposedly reaches over 13 billion years back. Many races know them as "The ones, who wait in the shadows". How this sentence reveals,they rarely interfered with other beings. They apparently engineered many galaxies and timelines of this universe. The Designers are said to have been born from the Big Bang and consist of the very elemental particles of reality.
Qccording to many legends they exist at many timelines at once.Their six dimensional physiology allows them to see everything there is,was,will be or could be in this universe.They are nothing but spirits imprisoned in organic constructs.
Obviously, this race is merely a legend and never actually existed although many individuals beg to differ.