Abstract: Thermostable viral and microbial polymerases exhibiting a combination of activities selected from proofreading (3?-5?) exonuclease activity, nick translating (5?-3?) nuclease activity, synthetic primer-initiated polymerase activity, nick-initiated polymerase activity, reverse transcriptase activity, strand displacement activity, terminal transferase activity, primase activity, and/or efficient incorporation of chain terminating analogs. Some of the polymerases provided herein include a first motif and a second motif. The first motif preferably has the sequence X1X2X3DX4PX5IELRX6X7X8, wherein X1 is I or V; X4 is F or Y; X8 is G or A; and X2, X3, X5, X6, and X7 are any amino acid. The second motif preferably has the sequence RX9X10X11KSANX12GX13X14YG, wherein X11 is G or A; X12 is F, L, or Y; X13 is L or V; X14 is I or L; and X9 and X10 are any amino acid.