Who plays the role of Grendel the monster in Beowulf?

There are several recent movie versions of the epic poem 'Beowulf'. Beowulf (1999) stars Christopher Lambert, Rhona Mitra and Vincent Hammond. The 2007 version stars Anthony Hopkins, Robin Wright, Angelina Jolie and John Malkovich. 2005's Beowulf & Grendel stars Gerard Butler and Ingvar Sigurdsson.