The Unicorn Club is a term used to refer to the illustrious selection of startups that are valued at $1 billion or more. From Uber to Airbnb, the members of the Unicorn club represent an impressive who's who of the world's fastest-growing companies. Fortune Magazine keeps a Unicorn List, the closest thing to an official rolodex of venture-backed tech companies that have hit the illustrious 10-figure valuation. 
Providing inspiration for any number of tech entrepreneurs with an idea and a dream, several of these companies were started by founders with engineering backgrounds. Here are some of the biggest and best.
Founded in 2002 and headquartered in Hawthorne, Calif., SpaceX is an aerospace manufacturer backed by billionaire Tesla CEO Elon Musk, a physicist and engineer. Musk’s father, Errol, was himself an electrical and mechanical engineer.
In 2010 SpaceX became the first private company to successfully launch and return a spacecraft from orbit. Musk continues to push new boundaries, with SpaceX focused on the development of reusable launch systems. As of February 2016, SpaceX boasted almost 5,000 employees.
One of the most valuable private consumer electronics companies in the world, Jawbone develops wearable products like the UP fitness tracker as well as music products, including its popular JAMBOX line. Jawbone was co-founded by Alexander Asseily, a product designer with a master’s degree in mechanical engineering. With headquarters in San Francisco and offices all over the world, has over 600 patents granted or pending related to its ecosystem and wearable tech manufacturing processes.
K.R. Sridhar, he founder of Bloom Energy, earned a bachelor's degree in mechanical engineering in his native India, followed by a masters in nuclear engineering and a PH.D. in mechanical engineering from the University of Illinois. After serving as a professor or aerospace and mechanical engineering at the University of Arizona - where he worked with NASA on research related to the sustainability of life on mars - he started Bloom Energy in 2001 with the goal of making clean, reliable energy affordable for everyone on earth.
In 2010, Bloom Energy debuted the Bloom Box, a solid oxide fuel cell that generates efficient, reliable power. Companies including Wal-Mart, Google and eBay have used Bloom’s technology for power generation.
Biomedical engineer Rony Abovitz got his start at MAKO Surgical Corp., a medical device company he co-founded in 2004. After departing MAKO, which makes surgical robotic equipment, Abovitz founded Magic Leap, a startup pioneering head-mounted displays that incorporate 3D technology. Magic Leap spent years operating in stealth mode, reportedly on augmented reality solutions.To date they have raised more than $500 million in venture capital from Google, Andreessen Horowitz and Kleiner Perkins among others.
What does it take for a startup to become a billion-dollar enterprise? A great idea? Connections? Resources? Luck? Or perhaps all of the above? With cautionary tales like the current scandal enveloping Theranos inc., should reaching the billion-dollar threshold necessarily be the end goal for a company? As ever, share your thoughts in the comments below...