Andy Murray and defending champion Grigor Dimitrov will play in June's Aegon Championships at Queen's Club, to be broadcast live on the BBC.
British number one Murray, who first won the event in 2009, will target a record-equalling fourth title.
World number 11 Dimitrov beat Murray in the Wimbledon quarter-finals last year.
"I've always had a special relationship with the [Aegon] Championships, from when I was given two wildcards early in my career," the Bulgarian said.
The 23-year-old, who beat Spaniard Feliciano Lopez to win the final at Queen's last year, added: "It is one of my favourite tournaments and winning the title last year was one of the best moments of my career so far.
"I am really happy that I will be coming back to defend my title and I look forward to playing in front of the great British crowds again."
World number six Murray, who lost in round three to Radek Stepanek last year, is seeking to emulate John McEnroe, Boris Becker, Lleyton Hewitt and Andy Roddick by winning the title four times.
"I've had some great moments on those grass courts," said the 27-year-old Scot. "It's where I won my first professional match and my first title in Britain.
"When you see the names on the trophy, it shows how difficult it is to win. The year I won Wimbledon, it came a few weeks after winning at Queen's, and it's perfect preparation."
The 2015 tournament takes place from 15-21 June.