Which unusual characters did Robert Kanigher add to Wonder Woman comics?

Robert Kanigher, who succeeded William Moulton Marston as the writer of Wonder Woman in 1948, introduced several unconventional elements to the series that often challenged the expectations of longtime readers.1

His additions to the mythos included:

• Younger versions of the heroine: Adventures featuring Wonder Girl and Wonder Tot.1
• Romantic suitors: Characters such as Merman and Birdman, along with their youthful counterparts, Mer-Boy and Bird-Boy.1
• Bizarre villains: A variety of unusual antagonists, including Angle Man, Paper-Man, and a sentient egg known as Egg Fu—the latter of which has been criticized as a "yellow peril" stereotype.1

These additions were so polarizing that Kanigher eventually took the unorthodox step of writing himself and artists Ross Andru and Mike Esposito into Wonder Woman no. 158 (1965) to "fire" the supporting cast he had created and return the character to her "Golden Age" roots.1