This is a report of Chandra , XMM-Newton , HST and ARC observations of an extended X-ray source at z = 0.59 .
The apparent member galaxies range from spiral to elliptical and are all relatively red ( i ^ { \prime } - K _ { s } about 3 ) .
We interpret this object to be a fossil group based on the difference between the brightness of the first and second brightest cluster members in the i ^ { \prime } -band , and because the rest-frame bolometric X-ray luminosity is about 9.2 \times 10 ^ { 43 } h _ { 70 } ^ { -2 } erg s ^ { -1 } .
This makes Cl 1205+44 the highest redshift fossil group yet reported .
The system also contains a central double-lobed radio galaxy which appears to be growing via the accretion of smaller galaxies .
We discuss the formation and evolution of fossil groups in light of the high redshift of Cl 1205+44 .