Schallert was probably best known as Martin Lane on "The Patty Duke Show". He also appeared as a wise teacher, Mr. Leander Pomfritt, on "The Many Loves of Dobie Gillis" and as "The Admiral" on "Get Smart". On the two former shows he worked opposite actress Jean Byron. Schallert made three guest appearances on CBS's "Perry Mason" between 1957 and 1962, including the role of Donald Graves in the series' fifth episode "The Case of the Sulky Girl," as Dr. Bradbury in the 1961 episode "The Case of the Misguided Missile," and as Len Dykes in the 1962 episode "The Case of the Melancholy Marksman." He played the role of Nilz Baris in the ' episode "The Trouble with Tribbles"; and much later he portrayed Varani, a Bajoran musician, in the ' episode "."