From Domain Food.
Rick Schwartz owned 3000+ domains back in 2000, in a February 2004 interview claims to own between 4300 and 4500 domains, experiencing 100,000 hits per day. Famous for selling men.com for $1.3 million in late 2003 and currently trying to market candy.com
Rick Schwartz: Domain King or Royal Pain? (Domain Name Journal)
The King of Domains (South Florida Business Journal)
Saeid Yomtobian - owned 78,472 domains when he threatened to sue VeriSign in July 2001! (aka Daniel Yomtobian or possibly his son, he also is responsible for Xupiter and their toolbar nonsense overriding links on a page - more info older info)
John Zuccarini - owns at least 5500 (possibly 8000) domains, solely based on the fact they are typos for more commonly used sites
(was arrested late 2003 and prosecuted - more info)
Court/WIPO cases Zuccarini has lost
Dan Parisi - owns (and currently trying to sell) the whitehouse.com as well as the 600+ domains of the sucks.com network of domains, and famous for losing the madonna.com WIPO dispute (more info)
"NicGod" - real name unknown, possibly Allen Ginsberg or Emil Lazarian, owns almost 3000 domains names with false whois data
Yun Ye (/Yee) - aka UltSearch operates a pay-per-click "business" out of Hong Kong with a portfolio of over 50,000 domains. He started hording domains in late 1998 and has accelerated the process over time. (As of August 2004 it is believed he manages over 113,000 domains.)
Michael Mann - aka BuyDomains along with partners Eric Cantor and Chip Yamasaki (and possibly others among a "10 person staff") market over 250,000 domains (he started in 1999, one year later he had 6000!). Perhaps in a bit of guilt Mann has also started Grassroots.org
Elequa (aka Thunayan Khalid AL-Ghanim) from Kuwait, owns more than more than 12,000 domains and is unofficially the "3-letter domain king". Elequa has between 2,500-3,000 3-letter .infos (15-20% of the all possibilities), 2,000 3-letter .nets and over 2,000 3-letter .orgs. He runs Future Media Architects and his own private registrar at i.net
Gary Kremen - never has one name been printed so often for so few domains, but what domains they are: match.com and sex.com! Gary only truly realized the worth of his registrations after sex.com was stolen from him and he had to spend everything to get it back. It is hard to get a clear understanding of the man behind such a domain, as one interview will make him look like a victim and the others like a very willing participant in the adult industry. Be sure to check out the story of the holiday greeting card that Gary commisioned.