Characterizing Icahn's recent letters as "false and misleading," Omidyar retorted that Icahn is making "unsubstantiated claims about our company -- and deliberately impugning the integrity of our directors."
Omidyar's letter follows one from Icahn to eBay shareholders on Monday, accusing CEO John Donahue of being incompetent while lashing out at two other prominent shareholders, venture capitalist Marc Andreessen and Intuit founder Scott Cook.
Icahn accused the two board members of undermining eBay's success for their personal gain.
As if that weren't enough, Icahn followed up with another letter to his own on Wednesday, ramping up his rhetoric by calling for the removal of the aforementioned parties from eBay's board while also labeling the leadership behind the digital marketplace as "dysfunctional."
Always one to avoid mincing words, Icahn wrote, "Let's end this charade."
Omidyar, also eBay's largest shareholder as noted by the man himself, outlined a rebuttal to Icahn's remarks, defending Donahoe, Cook, and Andreessen.
Icahn has been at the center of a number of hostile debates in the tech world lately, repeatedly going head-to-head against the corporate leaders of high-profile companies within his investment portfolio -- notably Dell and Apple.
The trouble with eBay started in January amid the company's fourth quarter earnings report. At the time, Icahn suggested (putting it mildly) that PayPal should be spun off.