Space: 1999 Eagle Transporter. The second-coolest toy of the Space: 1970 era was Kenner's 18" Alien. And the third...
Kenner's Bionic Bigfoot from the Six Million Dollar Man.
Unlike the terrifying-but-desperately-coveted Alien, I did own one of these beauties for a while, although, oddly, I never had a Steve Austin action figure. This meant that Bigfoot usually battled my Mego Superman or teamed up with the Planet Of The Apes Gorilla Soldier against Captain Kirk. Man, those were epic backyard confrontations! Bigfoot wasn't particularly well-articulated, but at a towering 15" he was damned imposing - especially when pitted against the smaller-scale Megos.
On a related note - which Bionic Bigfoot did you prefer - Ted Cassidy or André the Giant?