Gates is No. 1 on the list for the 10th straight year. His net worth is estimated at $46.6 billion, still less than half the $100 billion it peaked at in 1998, but up about 13% from the $40.7 billion Forbes attributed to him in 2003. Microsoft's other co-founder, Paul Allen, is fifth on the list at $21 billion.
Financier Warren Buffett increased his net worth by $12.4 billion to $42.9 billion, significantly narrowing the gap between him and Gates, with whom he competes in bridge tournaments.
In all, the magazine listed 587 billionaires around the world, up from 476 in 2003. Their total net worth jumped to $1.9 trillion from the $1.4 trillion the magazine counted in 2003.
There were 56 billionaires who returned to the list after dropping off in the past few years, including Yahoo Inc. founders David Filo ($2.2 billion) and Jerry Yang ($1.9 billion). They returned to find their upstart search-engine rivals, Google's Sergey Brin and Larry Page ($1 billion each), making their debut on the list.