The Sonex is the brainchild of John T. Monnett, who also designed the:
Monnett I - single-seat sports plane (first flown 1960s)
Monnett II Sonerai - single-seat Formula V racer (first flown 1971)
Monnett Sonerai II - two-seat sports plane (first flown 1973)
Monnett Monerai S - single-seat glider (first flown March 1978)
Monnett Monex - single-seat experimental (first flown September 1980)
Monnett Moni - single-seat motor glider (first flown July 1981)
Monnett Monerai P - single-seat motor glider (first flown early 1984)
Sonex Aircraft Sonex - two-seat sports plane (first flown 1997)
Sonex Aircraft Waiex - Sonex with butterfly tail
Sonex Aircraft Xenos - two-seat motor glider."