Fantastic Four (1961 1st Series) #129 VF+ [1st appearance of Thundra.]
Published Dec 1972 by Marvel.
"The Frightful Four...Plus One!" Part 1 of 2. Guest-starring Medusa and Thundra (first appearance). Script by Roy Thomas. Pencils by John Buscema. Inks by Joe Sinnott. Cover by John Buscema, Frank Giacoia, and John Verpoorten. The Fantastic Four have returned to the Baxter Building after finishing their adventure with the Mole Man last issue. But things don't remain quiet for long as Johnny surprisingly announces his intention to go to the Great Refuge! And in a flash the Human Torch departs for the Hidden Land to see Crystal! Moments later another bombshell drops when Agatha Harkness informs Reed and Sue that she can no longer take care of young Franklin. After all the outbursts, Ben decides to go for a walk across town to clear his head. However, he walks right into a battle between the past and present members of the Frightful Four! At an abandoned construction site, Ben Grimm and Medusa fight for their lives against the Sandman, Trapster, Wizard, and Thundra! First appearance of Thundra. Cameo appearance by Black Bolt. 32 pages Cover price $0.20.