Here are all the Grassclan cats that have left to join StarClan...

Leaders
Grassstar. (Killed by badger saving Clan-mates) {orkneymatrix}
Crowstar. (Murdered by Daisy, a rogue, sacrificing herself to save her Clan) {orkneymatrix}
Tigerstar. (Lost last life to greencough) {orkneymatrix}
Angelstar. (Heart attack/sickness) {orkneymatrix}

Medicine Cats
Rosepaw. (Mysteriously murdered. Later discovered she was killed by a rogue, Daisy and StarClan had not stopped this because she was not destined to be a medicine cat) {Mousefang}

Warriors
Seasnake. (Killed by badger) {segafan}
Magmafur. (Hit by monster)
Ashfield. (Hit by monster saving sister, Magmafur)
Skyfern. (Mysteriously murdered. Later it was discovered she was killed by a rogue, Daisy) {hellomia}
Lilydawn. (Killed by badger) {orkneymatrix}
Squirrelflight. (Killed by badger) {orkneymatrix}
Blackthorn. (Greencough) {Blackthorn}
Cinderheart. (Greencough) {Cinderheart}

Apprentices
Flamepaw. (Murdered by a rogue, Daisy) {Mousefang}
Onepaw. (Murdered by a rogue, Daisy when trying to save Whitepaw, her love) {orkneymatrix/MzScotGirl01}
Olivepaw. (Hit by monster) {orkneymatrix/MzScotGirl01}

Kits
Earthkit. (Murdered by a rogue, Daisy)
Bluekit. (Greencough)
Greenkit. (Greencough)
Molekit. (Greencough)
Heatherkit. (Greencough/weakness)

Elders
Lilyfall. (Illness) {ScottishChic}
Mousefur. (Mysteriously murdered. Later revealed she was killed by Daisy, a rogue) {brightclaw}
Flashstep. (Old age) {brownstar}