Themistocles Nicholas "Themi" Leftheris (born December 20, 1982) is an American-South Korean pair skater.

Leftheris had a tryout with Naomi Nari Nam in April 2005, two weeks after she decided to switch to pair skating.

In the 2006–07 season, Nam and Leftheris won the bronze medal at their Grand Prix assignment, 2006 Skate America.

They won the bronze medal at the 2007 U.S. Championships behind Rena Inoue / John Baldwin and Brooke Castile / Benjamin Okolski.

On August 24, 2007, Nam underwent surgery to remove a bone spur and to repair torn cartilage in her right hip.

[8] Nam/Leftheris were coached by Peter Oppegard and Karen Kwan-Oppegard at the EastWest Ice Palace in Artesia, California.