Robert Thomas Bigelow (born May 12, 1945) is a Nevada-based real estate and aerospace entrepreneur best known as the founder of Bigelow Aerospace, a company focused on expandable space habitat technology. He has been one of the most significant private funders of UAP research in the United States, spending an estimated $300 million or more of his own money on paranormal and UAP investigation over several decades.

Bigelow's interest in UAP was shaped in part by a family story involving his grandparents, who claimed to have witnessed a close encounter with an anomalous craft. He founded the National Institute for Discovery Science (NIDS) in 1995, a private research organization that investigated paranormal and UAP phenomena using scientific methodologies. NIDS acquired the infamous Skinwalker Ranch in Utah in 1996, a property with a long history of reported anomalous activity, and conducted systematic observation there for years.

Bigelow was a close associate of Senator Harry Reid, who leveraged this relationship to help establish the Advanced Aerospace Threat Identification Program (AATIP) in 2007. The primary contractor for AATIP research was Bigelow Aerospace Advanced Space Studies (BAASS), which received approximately $22 million in government funding to study UAP reports and related materials. Former AATIP director Luis Elizondo has stated that some recovered UAP-related materials were stored at Bigelow Aerospace facilities.

Bigelow has made remarkably candid public statements about UAP, including a 2017 CBS 60 Minutes interview in which he stated he was "absolutely convinced" that extraterrestrial visitors are present on Earth and that "there has been and is an existing presence, an ET presence." These statements are notable for their directness from a businessman with significant government contracts.