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Created by writer Len Wein and artist Dave Cockrum , he first appeared in " Giant-Size X-Men " # 1 ( May 1975 ) .
 Len Wein, Dave Cockrum
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Len Wein, Dave Cockrum