Kevin O'Leary / O'Leary Ventures

Kevin O'Leary — "Mr. Wonderful" — is a Canadian-Irish businessman, investor, and the most openly mercenary cast member of ABC's Shark Tank. Born in Montreal in 1954, he co-founded SoftKey Software Products in his mother's basement in 1986, rolled it up through a series of acquisitions (The Learning Company, Compton's, Broderbund), and sold the combined entity to Mattel in 1999 for $4.2 billion in what would shortly become one of the worst acquisitions in corporate history — Mattel wrote down $3.5B within a year and the CEO was fired. O'Leary walked with roughly $600M and has never publicly apologized for the outcome. He founded O'Leary Funds (mutual funds) in 2008 — wound down in 2015 after chronic underperformance — and now runs O'Leary Ventures, investing personally and via his production company O'Shares ETFs.