Franz Jarnach (1944 – 16 January 2017), also known by his stage name Mr. Piggi, was a German actor and musician.

He was best for his role as Schildkröte in the improvisation comedy series Dittsche. He appeared in series at least 188 times between 2004 and 2014. He was a pianist for the 1960s British beat group Lee Curtis and the All-Stars. He appeared on the music program Beat-Club with the group twice. He was also a member of the rock band The Rattles during the early 1990s.

Jarnach was born in the Bad Godesberg, today a district of Bonn, North Rhine-Westphalia. His father, Philipp Jarnach (1892–1982), was a noted composer.

Jarnach died from a heart attack on 16 January 2017 in Hamburg. He was 72.