The Parker 51 was marketed as "The World's Most Wanted Pen" upon its introduction in 1941.
This slogan was particularly effective due to circumstances surrounding World War II. During that time, restrictions were placed on the production of consumer goods in the United States to prioritize resources for the war effort. The "most wanted" label played on this scarcity, creating a sense of desire and exclusivity around the Parker 51.
While other pens might be considered highly sought after by collectors today based on rarity, historical significance, or current market value, the Parker 51 explicitly used the phrase "The World's Most Wanted Pen" as part of its original marketing campaign.
