In the field of voice forensics, the ability to perform effective speaker recognition from input audio streams is an important task. However, in many situations, individuals willchange the manner in which they produce their speech due to the environment (i.e., Lombard Effect), their speaker state (i.e., emotion, cognitive stress), and secondary tasks (i.e., task stress at hand, both physical and/or cognitive). Automatic recognition schemes for both speech and speaker ID are impacted by the variability introduced in these conditions. Extensive research in the field of speech under stress has been performed for speech recognition, primarily for low-vocabulary isolated-word recognition. However, limited formal research has been performed for speaker ID/verification primarily due to the lack of effective corpora in the field. This chapter addresses speech under stress including Lombard effect for the purposes of speaker recognition. Domains where stress/variability occur (Lombard Effect, Physical Stress, Cognitive Stress) will first be considered. Next, to perform effective speaker recognition it is necessary to detect if a subject is under stress, which is a useful trait in and of itself for voice forensics and biometrics, and therefore we consider prior research on the detection of speech under stress. Next, the impact of stress on speaker recognition is considered, and finally we address ways to improve speaker recognition in these domains (TEO features, alternative sensors, classification schemes, etc.). While speech under stress has been considered, the domain of speaker recognition represents an emerging research aspect which deserves further investigations.