Olly, Syd and Millie were the official mascots of the 2000 Summer Olympics in Sydney, representing air, soil and water. Olly (from Olympics) the kookaburra represents the Olympic spirit of generosity. Syd (from Sydney) the platypus, represents the environment as well as the activity and energy of Australia and their population. Millie (from Millennium) the echidna, knows everything about technology and numerical data. The mascots were designed by Matthew Hattan and Jozef Szekeres.
References
Olly, Syd and Millie Wikipedia(Text) CC BY-SA