Harlequins have announced James Horwill will replace Danny Care as club captain at Twickenham Stoop from next season.
Horwill, a former Australia captain, joined Harlequins in 2015 and recently signed a new three-year contract with the club.
The 32-year-old lock said: "I'm very humbled and honoured to be asked to captain such a great club. It's certainly something that I won't be taking lightly.
"The hard work for us as a squad starts now and we want to make Harlequins as successful as it can be."
Horwill will be the fourth permanent captain at The Stoop in just four years.
Former England captain Chris Robshaw was replaced by Joe Marler in 2014, before Danny Care replaced Marler just a year later.
Care led Harlequins to a sixth-place finish in the Aviva Premiership last season, and Horwill believes they can improve on that next term.
"The exciting thing is we haven't reached our potential," Horwill said. "We have played well in parts, but we have more to give, both in an individual capacity and as a group."
Horwill played for Super Rugby side Queensland Reds before moving to Harlequins. He has played 62 times for the Wallabies and captained them to a third place finish at the 2011 World Cup.
However, his international career looks to be over, as Australia head coach Michael Cheika has not picked him since dropping him for the 2015 World Cup.