Tom Cross (born 1976), also known as Decius, is an American computer security expert and hacker.

Cross was born in 1976 in Toronto, Ontario, Canada, and grew up in Tennessee.

His father worked in telecommunications policy and his mother was a Registered Nurse's Assistant.

From 1999 to 2000, he was Chief Engineer at Dataway, a computer security firm in San Francisco.

In 2001, he founded Industrial Memetics, which developed the popular collaborative blogging community MemeStreams.