Ajahn Thānissaro (also known as Ajahn Geoff) is an American Buddhist monk who studied for ten years under the forest master Ajahn Fuang Jotiko (himself a student of Ajahn Lee). Since 1993, he has served as abbot of the Metta Forest Monastery in San Diego County, California—the first monastery in the Thai Forest Tradition in the U.S.—which he cofounded with Ajahn Suwat Suvaco.
Ṭhānissaro Bhikkhu is perhaps best known for his translations of the Sutta Pitaka—almost 1000 suttas in all—as well as translations from the Dhamma talks of the Thai forest ajahns.